Subtitles section
Repeat sentence
Subtitles mode
Full screen
Previous
Next
x 1.0
Playback speed
More

What Is The Magnus Force?

Video vocabulary

either

Copy vocabulary

US / ˈaɪðə(r) /

UK / ˈiðɚ, ˈaɪðɚ /

A1
  • adjecitve
  • One of two (used when there is a choice of two)
  • adverb
  • (After negative statements) likewise, in addition
  • conjunction
  • Used as the first of two connected things
  • determiner
  • Used as the first of two connected things
  • pronoun
  • The one or the other

here

Copy vocabulary

US / hɪə(r) /

UK / hɪr /

A1
  • adverb
  • In this place; at this location, position or time

try

Copy vocabulary

US / traɪ /

UK / traɪ /

A1
  • noun
  • Act of putting the ball over the rugby goal line
  • verb
  • To make an effort, to attempt to do something
  • To examine someone or something in a court of law
  • To test to see if it is good or you like it
  • To make a person go through hardship; test
  • To examine something to see if it works

actually

Copy vocabulary

US / ˈæktʃuəli /

UK / ˈæktʃuəli /

A1
  • adverb
  • Used to add new (often different) information

gravity

Copy vocabulary

US / ˈgrævəti /

UK / ˈɡrævɪti /

B1
  • noun
  • (Of a situation) extreme seriousness
  • Force making things fall towards the ground

third

Copy vocabulary

US / θɜ:d /

UK / θɜ:rd /

A1
  • adjecitve
  • 3rd: Number after second

strike

Copy vocabulary

US / straɪk /

UK / straɪk /

A2
  • noun
  • A punch or hit
  • Fact of not hitting the ball when playing baseball
  • Refusal to work to get more pay, protest something
  • verb
  • To hit something
  • To suddenly become (e.g. rich)
  • To have an idea occur to you

axis

Copy vocabulary

US / ˈæksɪs /

UK / ˈæksɪs /

B1
  • noun
  • A line about which a rotating body turns

golfer

Copy vocabulary

US / ˈgɒlfə(r) /

UK / ˈgɑ:lfə(r) /

A2
  • noun
  • Someone who plays the game of golf

exactly

Copy vocabulary

US / ɪgˈzæktli /

UK / ɪɡˈzæktli /

A1
  • adverb
  • No more and no less than; precisely

parabolic

Copy vocabulary

US / ˌpærə'bɒlɪk /

UK / ˌpærəˈbɑlɪk /

A1
  • adjecitve
  • Having the form of a parabola

after

Copy vocabulary

US / 'ɑ:ftə(r) /

UK / ˈæftɚ /

A1
  • adverb
  • Later than another time, or behind something
  • conjunction
  • Following something before
  • preposition
  • When an event happened or time has passed

episode

Copy vocabulary

US / 'epɪsəʊd /

UK / ˈɛpɪˌsod /

B1
  • noun
  • One separate event in a series of events
  • Show which is part of a larger story

net

Copy vocabulary

US / net /

UK / nɛt /

A2
  • adjecitve
  • Remaining amount after something is taken away
  • noun
  • Internet
  • Crossed rope, fibers with partly open pattern
  • Crossed ropes that make up the back of a goal
  • verb
  • To catch or cover something in a mesh, often fish
  • To gain or earn a certain amount of money
  • To hit a ball into a goal during a sports event

will

Copy vocabulary

US / wɪl /

UK / wɪl /

A1
  • noun
  • Desire or choice of someone
  • Document saying who gets your money when you die
  • Strong desire to do something; determination
  • Desire to do something; strong wish to do
  • other
  • Used with verbs to express the future
  • verb
  • To leave property to someone after your death
  • To use mental effort to make something happen
  • Am (is, are) likely to do
  • To influence someone to do something
  • To make something happen by strongly wanting it

flow

Copy vocabulary

US / fləʊ /

UK / flo /

A2
  • noun
  • Amount of something that moves through an area
  • verb
  • To move steadily and easily in a certain direction

fairly

Copy vocabulary

US / 'feəlɪ /

UK / ˈfɛrli /

A2
  • adverb
  • Quite; pretty; between very and a little
  • In a manner that is right and acceptable

side

Copy vocabulary

US / saɪd /

UK / saɪd /

A1
  • adjecitve
  • In addition to the central or most important thing
  • Next to, or very close to, the right or left of
  • noun
  • Position or opinion that is opposite to another
  • Right or left part of a person's body
  • Feature of someone's personality
  • Straight edge of an object
  • One of two or more groups fighting each other
  • verb
  • To decide to agree with one point, not the other

quite

Copy vocabulary

US / kwaɪt /

UK / kwaɪt /

A1
  • adverb
  • Not very; fairly
  • Very; In a complete or total manner

not

Copy vocabulary

US / nɒt /

UK / nɑt /

A1
  • adverb
  • Word indicating the negative
  • (Used to form the negative of verbs)

whole

Copy vocabulary

US / həul /

UK / hol /

A1
  • adjecitve
  • Complete or full; all of
  • Being in a good condition
  • noun
  • Complete amount or sum; total

projectile

Copy vocabulary

US / prəˈdʒektaɪl /

UK / prəˈdʒɛktəl, -ˌtaɪl /

C1
  • noun
  • Something thrown or fired at a target

would

Copy vocabulary

US / wʊd /

UK / wʊd /

A1
  • other
  • Used to indicate something imagined
  • Used to ask or request something politely
  • Verb used to indicate possibility, request etc.
  • Used to indicate a preference
  • Used to indicate a reaction
  • Indicates something that occurred repeatedly
  • Used to indicate willingness or ability to do

but

Copy vocabulary

US / bət /

UK / bʌt,bət /

A1
  • conjunction
  • Used before you say something different, opposite

equal

Copy vocabulary

US / 'i:kwəl /

UK / ˈikwəl /

A1
  • adjecitve
  • Same in shape, size, or number
  • verb
  • To add up or be the same as

law

Copy vocabulary

US / lɔ: /

UK / lɔ /

A1
  • noun
  • Field of study that relates to the legal profession
  • A rule made and enforced by a government
  • System or rules made by the government

magnus

Copy vocabulary

US / ˈmægnəs /

UK / /

A1

now

Copy vocabulary

US / naʊ /

UK / naʊ /

A1
  • adverb
  • At the present time or moment
  • Right away or in the next possible moment
  • Used to refer to something that just happened
  • Time between the present and a moment in the past
  • conjunction
  • Resulting from or because of something

same

Copy vocabulary

US / seɪm /

UK / sem /

A1
  • adjecitve
  • Being equal in quality and amount
  • Identical; not different
  • Not changing; constant

tune

Copy vocabulary

US / tju:n /

UK / tun, tjun /

A2
  • noun
  • Group of musical notes that make a pleasant sound
  • verb
  • To make adjustments to equipment to make it better
  • To adjust to be at the right musical pitch
  • To modify how something operates, looks, e.g. car

sport

Copy vocabulary

US / spɔ:t /

UK / spɔː(r)t /

A1
  • noun
  • Something that is done for fun, e.g. football
  • Game or physical exercise with rules
  • Someone with a good attitude when things go badly
  • verb
  • To do something for fun, e.g. playing with animals
  • To wear, or show something off by wearing it

slow

Copy vocabulary

US / sləʊ /

UK / sloʊ /

A1
  • adjecitve
  • Lacking activity, busyness or excitement
  • (Clock) showing time earlier than the actual time
  • Having difficulty understanding simple things
  • Moving or happening without speed; not fast
  • verb
  • To move, with less speed than before
  • To move or go without much speed

expect

Copy vocabulary

US / ɪk'spekt /

UK / ɪkˈspɛkt /

A1
  • verb
  • To believe something is probably going to happen

want

Copy vocabulary

US / wɔnt /

UK / wɑnt, wɔnt /

A1
  • noun
  • Something you desire or wish for
  • State or condition of poverty
  • verb
  • To desire or wish for something; hope for a thing

tennis

Copy vocabulary

US / 'tenɪs /

UK / 'tenɪs /

A2
  • noun
  • Game played by hitting a ball over a net

weigh

Copy vocabulary

US / weɪ /

UK / weɪ /

A2
  • verb
  • To balance things against each other
  • To consider something carefully to form an opinion
  • To determine the weight of, using scales

can

Copy vocabulary

US / kæn /

UK / kən,kæn /

A1
  • noun
  • A metal container for storing food
  • other
  • Able to; have the skill to; have the time to
  • verb
  • To have permission to
  • To be possible to do
  • To preserve food by sealing it in a metal container

exert

Copy vocabulary

US / ɪgˈzɜ:t /

UK / ɪgˈzɜ:rt /

B2
  • verb
  • To make something have an effect on something else

ramp

Copy vocabulary

US / ræmp /

UK / ræmp /

B2
  • noun
  • Path that increases in height as you walk up it
  • verb

towards

Copy vocabulary

US / tə'wɔ:dz /

UK / 'təuədz, twɔ:dz /

A1
  • preposition
  • In the direction of someone or something

advantage

Copy vocabulary

US / əd'vɑ:ntɪdʒ /

UK / ædˈvæntɪdʒ /

A2
  • noun
  • Thing making the chance of success higher
  • A positive point about something

effect

Copy vocabulary

US / ɪ'fekt /

UK / ɪˈfɛkt /

A1
  • noun
  • An advantage, benefit
  • Change brought about by a cause; result

cannonball

Copy vocabulary

US / ˈkænənbɔ:l /

UK / ˈkænənˌbɔl /

C2
  • noun
  • Solid ball of metal fired from a cannon

sense

Copy vocabulary

US / sens /

UK / sɛns /

A1
  • noun
  • Certain mental feeling or emotion
  • Normal or clear state of mind
  • Meaning of a particular word, phrase or text
  • verb
  • To perceive using sight, sound, taste touch etc.
  • To recognize the presence of something

surprising

Copy vocabulary

US / səˈpraɪzɪŋ /

UK / sərˈpraɪzɪŋ /

A1
  • adjecitve
  • Making you feel a bit shocked because unexpected
  • verb
  • To do something that another person didn't expect

down

Copy vocabulary

US / daʊn /

UK / daʊn /

A1
  • adjecitve
  • Being sad, sick, or unhappy
  • Not operating, working, or functioning as expected
  • adverb
  • In a sitting or lying position
  • Towards or on the ground, floor, or bottom
  • Written or copied onto a piece of paper or book
  • noun
  • A period of play in American Football
  • The soft, smooth hairs that cover a bird's body
  • preposition
  • Along something's path, course, or direction
  • Going from a higher position to a lower position
  • verb
  • To eat or drink very quickly and without stopping

force

Copy vocabulary

US / fɔ:s /

UK / fɔrs, fors /

A1
  • noun
  • Group of persons trained for military action; army
  • Pressure; attraction
  • The use of physical strength/violence to persuade
  • verb
  • To use physical strength or violence to persuade

then

Copy vocabulary

US / ðen /

UK / ðɛn /

A1
  • adverb
  • A time that is not now
  • Following another thing in time or arrangement
  • Following on reasonably from what was just stated
  • At that time, not now

student

Copy vocabulary

US / ˈstju:dnt /

UK / ˈstudnt, ˈstjud- /

A1
  • noun
  • Person studying at school

topspin

Copy vocabulary

US / ˈtɒpspɪn /

UK / ˈtɑ:pspɪn /

C2
  • noun
  • Forward spin of a moving ball

backspin

Copy vocabulary

US / ˈbækspɪn /

UK / ˈbækˌspɪn /

A1
  • noun
  • Spin (usually of a moving ball) that retards or reverses the forward motion

case

Copy vocabulary

US / keɪs /

UK / kes /

A1
  • noun
  • Container used to carry things, e.g. clothes
  • Set of facts about a crime
  • Set of facts about an event
  • Example or instance of something
  • verb
  • To find out about a place, as in planning to steal

deflect

Copy vocabulary

US / dɪ'flekt /

UK / dɪˈflɛkt /

B2
  • verb
  • To cause to turn in a different direction
  • To prevent or avoid something having an effect on

find

Copy vocabulary

US / faɪnd /

UK / faɪnd /

A1
  • noun
  • Object discovered by chance
  • Things that have been discovered from searching
  • verb
  • To become aware of something that is happening
  • To discover or meet by chance
  • To decide if someone is guilty of a crime, or not
  • To learn through study, research, or effort
  • To discover something by looking for it

mean

Copy vocabulary

US / mi:n /

UK / min /

A1
  • adjecitve
  • Being good at
  • Nasty; unkind
  • Not liking to spend money; cheap; stingy
  • noun
  • Average of a set of numbers
  • verb
  • To express a particular idea or thought
  • To intend to do something in particular
  • To have a particular meaning or value

watch

Copy vocabulary

US / wɒtʃ /

UK / wɑtʃ /

A1
  • noun
  • Period of time someone is responsible for guarding
  • Device you wear on your wrist that shows the time
  • Official warning statement, e.g. of bad weather
  • verb
  • To keep in check, manage, or control something
  • To look at something for entertainment, e.g. TV
  • To guard a place or people; protect child, etc.
  • To look at carefully to work out what is happening
  • To protect and care for someone or something

bottom

Copy vocabulary

US / 'bɒtəm /

UK / ˈbɑtəm /

A2
  • adjecitve
  • Concerning the part under something, e.g. a vase
  • noun
  • The part of your body you sit on
  • Lowest position, often in a company or contest
  • Lowest part of something; part on which it rests
  • Lowest level, part or point of an object
  • The part under something, e.g. a vase
  • verb
  • To hit the lowest part of something

cylinder

Copy vocabulary

US / ˈsɪlɪndə(r) /

UK / ˈsɪləndɚ /

B2
  • noun
  • Tube shape with flat ends

drag

Copy vocabulary

US / dræɡ /

UK / dræɡ /

A2
  • noun
  • Force of air pushing back against a plane car etc.
  • Boring or annoying thing/activity
  • verb
  • To reluctantly move or go somewhere
  • To feel that progress or time is moving slowly
  • To pull something heavy or difficult along the ground

happen

Copy vocabulary

US / 'hæpən /

UK / ˈhæpən /

A1
  • verb
  • To take place or occur

example

Copy vocabulary

US / ɪgˈzɑ:mpl /

UK / ɪɡˈzæmpəl /

A1
  • noun
  • Thing, person which represents a category

ball

Copy vocabulary

US / bɔ:l /

UK / bɔl /

A1
  • noun
  • Large dance where people dress formally
  • Small round object often used in a game or sport

cause

Copy vocabulary

US / kɔ:z /

UK / kɔz /

A2
  • noun
  • Belief, goal or organization that people support
  • Reason for
  • verb
  • To make something happen; create effect or result

about

Copy vocabulary

US / ə'baʊt /

UK / əˈbaʊt /

A1
  • adverb
  • To be ready to; going to
  • Nearly; approximately; roughly
  • Near; next to; close to
  • In every direction; in the area of
  • preposition
  • Concerning or of (a topic)

why

Copy vocabulary

US / waɪ /

UK / hwaɪ, waɪ /

A1
  • adverb
  • Question word to ask for a reason
  • exclamation
  • (Used to express surprise or approval)

friction

Copy vocabulary

US / ˈfrɪkʃn /

UK / ˈfrɪkʃən /

B2
  • noun
  • Disagreement between two or more people
  • Force preventing motion between bodies in contact

difficult

Copy vocabulary

US / 'dɪfɪkəlt /

UK / ˈdɪfɪˌkʌlt, -kəlt /

A1
  • adjecitve
  • Hard; not easy; you need to work hard to do it

flight

Copy vocabulary

US / flaɪt /

UK / flaɪt /

A2
  • noun
  • Act of leaving a place, usually to escape danger
  • Trip by plane, helicopter etc.

object

Copy vocabulary

US / 'ɒbdʒɪkt /

UK / ˈɑbdʒɪkt /

A2
  • noun
  • Something you can see or touch, but is not alive
  • Goal or purpose of a particular plan or activity
  • The thing that the action of a verb acts upon
  • verb
  • To disagree; to protest against an idea or plan

airflow

Copy vocabulary

US / ˈeəfləʊ /

UK / ˈerfloʊ /

C2
  • noun
  • Movement of air around objects

just

Copy vocabulary

US / dʒʌst /

UK / dʒʌst /

A1
  • adjecitve
  • Proper or appropriate; as is deserved
  • Doing or being what is right or fair
  • Legally correct; having enough evidence
  • adverb
  • Almost; nearly
  • Exactly at the time of
  • Exactly (the same as, like)

talk

Copy vocabulary

US / tɔ:k /

UK / tɔk /

A1
  • noun
  • Style of speaking
  • Discussion between two countries
  • Giving information in front of people; lecture
  • Saying things or ideas to someone with words
  • verb
  • To make a formal speech about something
  • To say things or ideas to someone with words

soon

Copy vocabulary

US / su:n /

UK / sun /

A1
  • adverb
  • At a time not long from now

sound

Copy vocabulary

US / saʊnd /

UK / saʊnd /

A1
  • adjecitve
  • Sensible, dependable and reliable
  • Unbroken or undisturbed, as of sleep
  • Firm or solid in structure
  • Sane; not mentally ill
  • Clearly reasoned; involving sense, good judgment
  • noun
  • Unique quality that characterizes a style of music
  • Waves traveling in air or water that can be heard
  • verb
  • To seem or appear to be, from what was said
  • To say in a clear deliberate manner
  • To make a noise, e.g. to ring a bell

such

Copy vocabulary

US / sʌtʃ /

UK / sʌtʃ /

A1
  • determiner
  • Being similar to
  • (Thing) as previously stated or referred to
  • adverb
  • (Used to emphasize the quality of an adjective)

play

Copy vocabulary

US / pleɪ /

UK / pleɪ /

A1
  • noun
  • Loose, free movement between two objects
  • Single action in a sports game
  • Performance in which people act in a theater
  • verb
  • To act as a character in a movie, or on stage
  • To perform music on an instrument
  • To use a device, e.g. a video game
  • To do something for enjoyment and fun
  • To do or perform a game or sport

this

Copy vocabulary

US / ðɪs /

UK / ðɪs /

A1
  • adjecitve
  • Used to indicate something already been discussed
  • Used to indicate something happening around now
  • adverb
  • An indication by a physical motion or gesture
  • A specific amount of
  • determiner
  • Person, thing, or idea near you
  • pronoun
  • Person, thing that has already been discussed

anticlockwise

Copy vocabulary

US / ˌæntiˈklɒkwaɪz /

UK / ˌæntiˈklɑːkwaɪz /

B1
  • adjecitve
  • In the opposite direction to the hands of a clock

surface

Copy vocabulary

US / 'sɜ:fɪs /

UK / ˈsɚfəs /

A2
  • adjecitve
  • Of the top layer; not deep or meaningful
  • noun
  • Top layer of the ground or of water
  • Nature or emotions that show, but may not be true
  • Outside or upper layer of something
  • verb
  • To give (road) a top layer
  • To appear after being hidden, unseen, or unknown
  • To come to the top of something; emerge
  • To come to the top level of water, mud, etc.

university

Copy vocabulary

US / ˌju:nɪ'vɜ:sətɪ /

UK / ˌjunɪˈvɜrsəti /

A1
  • noun
  • High-level educational institution; college

buoyant

Copy vocabulary

US / ˈbɔɪənt /

UK / ˈbu:jənt /

B2
  • adjecitve
  • Capable of floating in a liquid

make

Copy vocabulary

US / meɪk /

UK / mek /

A1
  • noun
  • Product made by a particular company; brand
  • verb
  • To arrange or prepare something e.g. dinner
  • To get to (a place) on time
  • To gain the status of (teacher, lawyer, etc.)
  • To create something by putting things together
  • To earn a certain amount of money at a job
  • To cause or force a person to do something
  • To cause something to happen or be formed

path

Copy vocabulary

US / pɑ:θ /

UK / pæθ, pɑθ /

A2
  • noun
  • Method of living leading to a particular result
  • Track made with stones, by walking over the ground

also

Copy vocabulary

US / 'ɔ:lsəʊ /

UK / ˈɔlso /

A1
  • adverb
  • In addition; too; in a similar way

how

Copy vocabulary

US / haʊ /

UK / haʊ /

A1
  • adjecitve
  • To what degree? in what amount?
  • adverb
  • (Used to explain the way to do something)
  • exclamation
  • For what purpose or reason?
  • (Used to ask someone or something's condition)

therefore

Copy vocabulary

US / ˈðeəfɔ:(r) /

UK / ˈðerfɔ:(r) /

A1
  • adverb
  • And so; for that reason

you

Copy vocabulary

US / jʊ /

UK / ju /

A1
  • pronoun
  • Person someone is speaking or writing to
  • Person or people in general

vertical

Copy vocabulary

US / ˈvɜ:tɪkl /

UK / ˈvɜ:rtɪkl /

B1
  • adjecitve
  • (Of a line, etc.) going up and down; not horizontal

spin

Copy vocabulary

US / spɪn /

UK / spɪn /

B1
  • noun
  • A dizzy feeling your head is turning around
  • A slant or hidden purpose, as in politicians' talk
  • A movement in a rapid turning motion
  • verb
  • To make a ball rotate when throwing it
  • To feel dizzy/confused, as in my head is spinning
  • To convert material such as cotton into thread
  • To move something in a rapid turning motion

predict

Copy vocabulary

US / prɪ'dɪkt /

UK / prɪˈdɪkt /

A2
  • verb
  • To guess or estimate what will or might happen

opposite

Copy vocabulary

US / ˈɔpəzit /

UK / ˈɑpəzɪt /

A2
  • adjecitve
  • Being totally different from
  • noun
  • Person, thing that is totally different to another
  • preposition
  • Across from or on the side facing something

alright

Copy vocabulary

US / ɔ:lˈraɪt /

UK / ɔlˈraɪt /

A2
  • adjecitve
  • OK; fine; good

forward

Copy vocabulary

US / 'fɔ:wəd /

UK / ˈfɔrwəd /

A1
  • adjecitve
  • Toward what is ahead; in front
  • Acting in a socially aggressive manner; pushy
  • adverb
  • Toward the front in place; in front
  • Toward a future time; to a more advanced state
  • verb
  • To send something to another address or person

other

Copy vocabulary

US / 'ʌðə(r) /

UK / ˈʌðər /

A1
  • adjecitve
  • A thing different from that mentioned
  • determiner
  • (Something) else; not the first (one)
  • pronoun
  • Being the one and only thing of that category

than

Copy vocabulary

US / ðən /

UK / ðən /

A1
  • conjunction
  • Used to compare two things that are not equal

alone

Copy vocabulary

US / ə'ləʊn /

UK / əˈlon /

A1
  • adjecitve
  • Apart from others
  • Without equal
  • adverb
  • Without anyone or anything else

let

Copy vocabulary

US / let /

UK / lɛt /

A1
  • verb
  • To allow someone to do something
  • Introducing a suggestion to do something together
  • To rent a house, etc. to others

little

Copy vocabulary

US / 'lɪtl /

UK / ˈlɪtl /

A1
  • adjecitve
  • Being short in length of time
  • Not great in size, amount, or degree; small
  • Being very young or younger than others
  • adverb
  • By an amount or degree that is not very much
  • Not often; rarely
  • noun
  • A person's name

the

Copy vocabulary

US / ðə /

UK / ðə /

A1
  • article
  • Used to refer to something already mentioned
  • Used to show there is only one of something
  • determiner
  • Used to describe all of a family

call

Copy vocabulary

US / kɔ:l /

UK / kɔl /

A1
  • noun
  • A order or request for action
  • The sound an animal makes, often when in danger
  • A correct prediction, e.g. a decision in a game
  • A short visit to a place or person
  • A decision by a referee or umpire in a game
  • verb
  • To make a request or order for action
  • (Animal) to make sounds to warn of danger
  • To announce the date of an election
  • To make a judgment about something
  • To give someone or something a name
  • To guess in advance the result or outcome
  • To visit a place or person for a short time
  • To phone someone
  • To speak, announce or shout in a loud voice

cross

Copy vocabulary

US / krɒs /

UK / krɔs, krɑs /

A2
  • adjecitve
  • Angry and upset
  • From one side of something to the other
  • noun
  • (Of animals) mixture of breeds in one animal
  • Person's name
  • verb
  • To put one thing over another e.g. arms
  • To breed one type of animal or plant with another
  • To not to agree with someone; oppose
  • To go from one side of something to the other
  • To meet at one point

leave

Copy vocabulary

US / li:v /

UK / liv /

A1
  • noun
  • Permission to do something
  • Vacation time; time off work
  • verb
  • To go away from; depart
  • To gift property to someone after you die
  • To allow something to continue happening
  • To let something remain unused or available
  • To let something or someone remain somewhere

far

Copy vocabulary

US / fɑ:(r) /

UK / fɑr /

A1
  • adjecitve
  • A long way away
  • Being a long way away
  • adverb
  • To a large degree or extent

screech

Copy vocabulary

US / skri:tʃ /

UK / skritʃ /

B2
  • verb
  • To make a loud high cry of pain, anger, or fear

rod

Copy vocabulary

US / rɒd /

UK / rɑ:d /

B1
  • noun
  • Straight, thin stick or bar
  • Pole with a line and hook to catch fish with

any

Copy vocabulary

US / 'enɪ /

UK / ˈɛni /

A1
  • adjecitve
  • One, or some, no matter which
  • pronoun
  • One (thing) of many; some

come

Copy vocabulary

US / kʌm /

UK / kʌm /

A1
  • verb
  • To arrive at a place
  • (Of mail) to be delivered
  • To move toward someone; go with someone
  • To reach a certain point or state

experiment

Copy vocabulary

US / ɪk'sperɪmənt /

UK / ɪkˈspɛrəmənt /

A2
  • noun
  • Test performed to assess new ideas or theories
  • verb
  • To create and perform tests to research something
  • To try something new that you haven't tried before

heavy

Copy vocabulary

US / 'hevɪ /

UK / ˈhɛvi /

A1
  • adjecitve
  • Greater in amount, degree, or severity than usual
  • Involving serious or strong emotions
  • Having a lot of weight

act

Copy vocabulary

US / ækt /

UK / ækt /

A1
  • noun
  • What someone did; action; behavior
  • A law or rule passed by a government we must obey
  • One of the parts that a stage play is divided into
  • verb
  • To behave in a certain way
  • To perform on a stage or in a movie

bit

Copy vocabulary

US / bɪt /

UK / bɪt /

A1
  • noun
  • Device put in a horse's mouth to control it
  • Small piece of something
  • verb
  • (E.g. of fish) to take bait and be caught

counterclockwise

Copy vocabulary

US / ˌkaʊntəˈklɒkwaɪz /

UK / ˌkaʊntərˈklɑ:kwaɪz /

A1
  • other
  • In a direction opposite to the direction in which the hands of a clock move
  • In the direction opposite to the rotation of the hands of a clock

discover

Copy vocabulary

US / dɪˈskʌvə(r) /

UK / dɪˈskʌvɚ /

A2
  • verb
  • To find something new that was not known before

take

Copy vocabulary

US / teɪk /

UK / tek /

A1
  • noun
  • Filming of a single scene for TV or the movies
  • verb
  • To accept something that is offered
  • To use a method of traveling, e.g. a bus or train
  • To use a camera to make (a photo)
  • To pick up something and go away with it
  • To study a subject in school
  • To attempt to pass (an exam)
  • To require a certain amount of time, money, space

direction

Copy vocabulary

US / də'rekʃn /

UK / dɪˈrɛkʃən, daɪ- /

A2
  • noun
  • When someone tells people what to do
  • Describes the way you are going, e.g. North

due

Copy vocabulary

US / dju: /

UK / du, dju /

A1
  • adjecitve
  • When something is required or expected
  • Owed to a person as a right
  • noun
  • Something you deserve; something you can expect

move

Copy vocabulary

US / mu:v /

UK / muv /

A1
  • noun
  • Act of moving a playing piece in chess, etc.
  • An action; doing something
  • Step taken to achieve a goal
  • verb
  • To cause someone to have certain emotions
  • To cause something to change to a different place
  • To change where people live or a business operates
  • To take action to do or achieve something

curve

Copy vocabulary

US / kə:v /

UK / kɚv /

A2
  • noun
  • Smooth rounded line that is not straight
  • verb
  • To make something bend into a rounded shape

between

Copy vocabulary

US / bɪˈtwi:n /

UK / bɪˈtwin /

A1
  • preposition
  • From one person, thing, or place, to another
  • In the space that separates two objects
  • Among two or more people who share something

they

Copy vocabulary

US / ðeɪ /

UK / ðe /

A1
  • pronoun
  • Two or more people, animals, or things

paper

Copy vocabulary

US / ˈpeɪpə(r) /

UK / ˈpeɪpər /

A1
  • adjecitve
  • Not existing in reality, or done infrequently
  • Made from the material that we use to make books
  • noun
  • Academic writing or a talk on a specific topic
  • Written test
  • Newspaper
  • Pages of a book are made from this

result

Copy vocabulary

US / rɪ'zʌlt /

UK / rɪˈzʌlt /

A2
  • noun
  • Something produced through tests or experiments
  • Final score of a competition, election or game
  • verb
  • To be the outcome of other causes and effects

show

Copy vocabulary

US / ʃəʊ /

UK / ʃo /

A1
  • noun
  • False display of love, emotion or action
  • An event for displaying or promoting goods
  • Play, opera or theater production
  • Presentation that is broadcast on TV or radio
  • verb
  • To be easily seen or displayed
  • To display your emotions or feelings
  • To let someone see something; display
  • To explain or teach how something is done
  • To lead someone somewhere; point them to something
  • To prove something to be true, correct
  • To reveal or allow something to be seen

travel

Copy vocabulary

US / ˈtrævl /

UK / ˈtrævəl /

A1
  • noun
  • Going to other places, esp. distant places
  • verb
  • To go to a place that is far away

court

Copy vocabulary

US / kɔ:t /

UK / kɔrt, kort /

A2
  • noun
  • Place king or queen meet people, makes laws etc.
  • Place where legal cases are decided
  • Large, flat area, to play tennis or basketball
  • verb
  • To act in a way to shows you wish to marry someone
  • To encourage dangerous behavior
  • To pay attention to someone to get their support

all

Copy vocabulary

US / ɔ:l /

UK / ɔl /

A1
  • adverb
  • Completely; totally
  • determiner
  • Being every one of something
  • pronoun
  • 100% of something; the complete amount

top

Copy vocabulary

US / tɒp /

UK / tɑp /

A1
  • adjecitve
  • Being good or great; excellent
  • Being the most in degree or quality
  • noun
  • Item of clothing covering shoulders to waist, hips
  • A cover or lid
  • Part (e.g. road) that is the furthest away
  • Highest or upper part or point of something
  • Best or highest status or position
  • Flat upper surface or edge of an object
  • Child's toy that spins on its point
  • Upper section or leaves of fruits and vegetables
  • Winning in a sport or contest
  • verb
  • To be higher or larger than a specific value
  • To arrive at the highest point of something
  • To put a cover or layer or over something
  • To kill; murder
  • To hold the highest position on a list
  • To be more important, successful or better than
  • To beat someone or win at a game

who

Copy vocabulary

US / hu: /

UK / hu /

A1
  • pronoun
  • Which person
  • Used to introduce information about people

set

Copy vocabulary

US / set /

UK / sɛt /

A1
  • adjecitve
  • Prepared for something; ready
  • noun
  • Complete group of something
  • Place where a television show or movie is filmed
  • Group of games in a tennis match
  • Device that receives radio or television signals
  • verb
  • To make a clock state or ring at a particular time
  • To decide upon or choose something
  • To make something ready for use (e.g. table)
  • To decide on a price for something
  • To become hard (of glue, concrete etc.)
  • To be located in a specific place or time
  • To put (e.g. a vase) down carefully in a place
  • To put someone in a certain condition or state
  • (Of the sun) to go lower than the horizon

seam

Copy vocabulary

US / si:m /

UK / sim /

B1
  • noun
  • Line where cloth, metal etc. are joined together

well

Copy vocabulary

US / wel /

UK / wɛl /

A1
  • adjecitve
  • Being in a fortunate, good condition or state
  • Healthy and in good condition
  • adverb
  • In an acceptable, proper, or successful manner
  • In a complete, total, or full manner
  • A great and considerable degree
  • In a successful way, in a good or satisfactory way
  • exclamation
  • Used to begin or continue a particular statement
  • Used to show you want to start saying something
  • Used to express that you are waiting for a reply
  • You say this to change the topic of a conversation
  • Used to indicate you are making a final remark
  • noun
  • Long deep hole in the ground to get water
  • verb
  • To cause your eyes to fill with tears

amount

Copy vocabulary

US / ə'maʊnt /

UK / əˈmaʊnt /

A1
  • noun
  • Quantity of something
  • verb
  • To add up to a certain figure

light

Copy vocabulary

US / laɪt /

UK / laɪt /

A1
  • adjecitve
  • Being bright making it easy to see; not dark
  • Being pale and lacking darkness of color
  • Not heavy; weighing only a little
  • adverb
  • Carrying few bags when traveling
  • noun
  • A source of energy that makes a room or area bright
  • Way in which something or someone is understood
  • verb
  • To cause something to burn; put a burning match to
  • To provide a way to see ahead

stuff

Copy vocabulary

US / stʌf /

UK / stʌf /

A1
  • noun
  • Generic description for things, materials, objects
  • verb
  • To push material inside something, with force

clockwise

Copy vocabulary

US / ˈklɒkwaɪz /

UK / ˈklɑkˌwaɪz /

B1
  • adjecitve
  • In the same direction as a clock's hands

few

Copy vocabulary

US / fju: /

UK / fju /

A1
  • pronoun
  • Not many, a small number

much

Copy vocabulary

US / mʌtʃ /

UK / mʌtʃ /

A1
  • adjecitve
  • Very; to a high level or degree
  • adverb
  • A lot; large amount; a high degree of
  • Nearly; basically
  • On many occasions; often
  • noun
  • A large amount; a great quantity

perpendicular

Copy vocabulary

US / ˌpɜ:pənˈdɪkjələ(r) /

UK / ˌpə:pənˈdɪkjəlɚ /

C1
  • adjecitve
  • Being at right angles to a given line or plane

for

Copy vocabulary

US / fə(r) /

UK / fɔr,fə /

A1
  • preposition
  • Used to show the purpose, or need of something

player

Copy vocabulary

US / ˈpleɪə(r) /

UK / ˈpleɚ /

A1
  • noun
  • Machine that plays recorded material
  • Person who plays a musical instrument
  • Person who plays games on devices
  • Person who plays sports

time

Copy vocabulary

US / taɪm /

UK / taɪm /

A1
  • noun
  • Speed at which music is played; tempo
  • Point as shown on a clock, e.g. 3 p.m
  • Number of hours, minutes needed to do something
  • Occasion when something happens
  • Period or occasion that something occurred
  • Period in history or the past
  • Something measured in minutes, hours, days, etc.
  • How long an event takes; duration
  • verb
  • To check speed at which music is performed
  • To choose a specific moment to do something
  • To measure how long an event takes, e.g. a race
  • To schedule something to occur at a specific moment

through

Copy vocabulary

US / θru: /

UK / θru /

A2
  • adjecitve
  • having finished using or doing something
  • adverb
  • From the beginning of something until the end
  • preposition
  • Over, in, across an entire thing or place
  • Allowing you to pass between, or to
  • By a particular way or process; by the use of

different

Copy vocabulary

US / ˈdɪfrənt /

UK / ˈdɪfrənt /

A1
  • adjecitve
  • Not of the same kind; unlike other things

like

Copy vocabulary

US / laɪk /

UK / laɪk /

A1
  • adjecitve
  • Being equal in status or kind to something else
  • Similar; the same
  • adverb
  • For example
  • preposition
  • Used as a filler; used to ad emphasis
  • In a way similar to the way something is done
  • Such as; for example
  • verb
  • To want to
  • To find something pleasing; to prefer something

people

Copy vocabulary

US / 'pi:pl /

UK / ˈpipəl /

A1
  • noun
  • Persons sharing culture, country, background, etc.
  • Men, Women, Children

that

Copy vocabulary

US / ðæt /

UK / ðæt, ðət /

A1
  • adjecitve
  • The person or thing being talked about
  • Used to identify something both the speakers know
  • adverb
  • Used to reinforce adjectives and adverbs
  • To such a degree
  • conjunction
  • Used to connect a noun clause
  • Used to introduce an adverbial clause
  • Used to introduce a noun clause
  • determiner
  • Used as a noun to refer to something
  • pronoun
  • Referring an object far away
  • Used to refer to the relative pronoun ‘which’

what

Copy vocabulary

US / wɒt /

UK / hwɑt, hwʌt, wɔt, wʌt,hwət, wət /

A1
  • pronoun
  • Thing or things that; the same kind as
  • Used to emphasize something you are about to say
  • adjecitve
  • Used to refer to a particular amount, or number
  • Used to place emphasis on a particular quality
  • adverb
  • To a certain degree
  • determiner
  • Question words used for asking for information
  • exclamation
  • Used to express excitement, shock, or surprise
  • Used to ask people to repeat something they said

hit

Copy vocabulary

US / hɪt /

UK / hɪt /

A1
  • noun
  • A planned killing, usually for money
  • Song, movie etc. that is successful
  • When someone strikes someone or something
  • Time when a player makes contact with the ball
  • Time when a website is accessed
  • verb
  • To have a negative impact on a person/place/thing
  • To press something, such as a button or switch
  • To suddenly realize the importance of something
  • To move your hand, a bat, etc. against with force
  • To fight, attack or damage something or someone
  • To arrive at a specific place, level, or goal
  • To make contact with the ball in a game or sport

stay

Copy vocabulary

US / steɪ /

UK / ste /

A1
  • noun
  • Legal order to stop or delay an action
  • Strong rope or wire that supports a ship's mast
  • Period of time spent living in or visiting a place
  • verb
  • To keep trying without giving up
  • To remain in the same place and not move away
  • To spend time visiting a place or someone's home

teaching

Copy vocabulary

US / ˈti:tʃɪŋ /

UK / ˈtitʃɪŋ /

A1
  • noun
  • The act of helping people learn
  • verb
  • To help someone learn or do something

tell

Copy vocabulary

US / tel /

UK / tɛl /

A1
  • verb
  • To (strongly) advise a person to do something
  • To be able to guess
  • To say or communicate information to someone
  • To inform, but without speaking; indicate
  • To have a negative effect on someone
  • To order someone to do something; command
  • To recognize something based on certain signs
  • To report something to an authority
  • To explain something or teach someone something

right

Copy vocabulary

US / raɪt /

UK / raɪt /

A1
  • adjecitve
  • Correct or true
  • The south side of you looking at the rising sun
  • adverb
  • Exactly in a place or time
  • Being appropriate for a particular event
  • In a straight or direct manner
  • noun
  • Something you are legally or morally allowed to do
  • Ideal of what is just and good
  • Political view based on conservatism
  • verb
  • To fix something previously wrong or unjust
  • To make upright, as a boat that has turned over

balloon

Copy vocabulary

US / bəˈlu:n /

UK / bəˈlun /

B1
  • noun
  • Thin bag of rubber filled with air, used as a toy
  • Large air-filled bag to carry people into the air
  • verb
  • To grow larger quickly; spring up suddenly
  • To travel in a large balloon

aware

Copy vocabulary

US / əˈwɛə /

UK / əˈwɛr /

A2
  • adjecitve
  • Knowing or feeling that something exists

get

Copy vocabulary

US / ɡet /

UK / ɡɛt /

A1
  • verb
  • To become affected by illness or disease
  • To begin to feel or understand an emotion or idea
  • To send or bring someone or something home, etc.
  • To go somewhere to obtain something
  • To (cause to) do a particular thing
  • To obtain, receive or be given something
  • To currently have
  • To prepare for use
  • To understand something being said or read

first

Copy vocabulary

US / fɜ:st /

UK / fɚst /

A1
  • adjecitve
  • 1st; Coming before all others in time or place
  • noun
  • Something that has not happened before
  • Position of the winner of a competition

have

Copy vocabulary

US / həv /

UK / hæv /

A1
  • verb
  • To drink, smoke, eat or use something
  • To experience the effects of something
  • To organize an event, or join in an activity
  • To own, possess, or hold something
  • To cause to happen or produce a particular effect

exercise

Copy vocabulary

US / 'eksəsaɪz /

UK / ˈɛksɚˌsaɪz /

A2
  • noun
  • Physical activity to increase health and strength
  • Set of questions in a text book
  • verb
  • To work out to become stronger and healthier
  • To retain your ability or practice your skills

away

Copy vocabulary

US / ə'weɪ /

UK / əˈwe /

A1
  • adjecitve
  • Not present
  • adverb
  • Disappear completely
  • Doing something with a lot of energy
  • Not here; far from here; in a different direction
  • To a different area, location

neglect

Copy vocabulary

US / nɪ'ɡlekt /

UK / nɪˈɡlɛkt /

B1
  • noun
  • Act of failing to do something important, required
  • State or condition of not receiving proper care
  • verb
  • To not do something that is important or required
  • To fail to take care of something; ignore

fall

Copy vocabulary

US / fɔ:l /

UK / fɔl /

A1
  • noun
  • Season after summer and before winter; Autumn
  • A drop in amount; decrease
  • Dropping from a standing position to the ground
  • verb
  • To drop in amount; to decrease
  • To come down from a higher position suddenly
  • To go from standing to the ground, by accident

with

Copy vocabulary

US / wɪð /

UK / wɪð, wɪθ /

A1
  • preposition
  • As an employee of a certain company
  • Against something or someone
  • By using something as a means
  • Due to; because of
  • Including
  • Possessing as a feature
  • Related to
  • (Of the manner/attitude by which you do something)
  • Used to express that people or things are together

halt

Copy vocabulary

US / hɔ:lt /

UK / hɔlt /

B1
  • verb
  • To stop, or cause something, e.g. a car, to stop

problem

Copy vocabulary

US / ˈprɒbləm /

UK / ˈprɑbləm /

A1
  • adjecitve
  • Causing trouble
  • noun
  • Something difficult to deal with or causes trouble
  • Question to show understanding of a math concept

onto

Copy vocabulary

US / ˈɒntə /

UK / ˈɑnˌtu, -tə, ˈɔn- /

A1
  • preposition
  • Towards a certain direction/into a certain area

see

Copy vocabulary

US / si: /

UK / si /

A1
  • verb
  • To go on a date with someone
  • To predict whether something is, or will be true
  • To understand what someone says
  • To use your eyes to look at something
  • To visit a place often for sightseeing or pleasure
  • To visit or meet with someone
  • To find out by waiting or looking
  • To watch (a game, movie or TV show)

baseball

Copy vocabulary

US / 'beɪsbɔ:l /

UK / ˈbesˌbɔl /

A2
  • noun
  • Small ball used in the game of baseball
  • Two teams of nine players hit a ball to score runs

cricket

Copy vocabulary

US / 'krɪkɪt /

UK / ˈkrɪkɪt /

B1
  • noun
  • Sport played by two teams hitting a ball with bats
  • Brown or black insect that makes short loud noises

know

Copy vocabulary

US / nəʊ /

UK / noʊ /

A1
  • verb
  • To be familiar with a person or place, thing
  • To feel sure or be convinced about something
  • To discover or be aware of something
  • To be able to distinguish
  • To have knowledge of things

whoa

Copy vocabulary

US / wəʊ /

UK / woʊ /

C1
  • exclamation
  • Tell someone to do something more slowly

air

Copy vocabulary

US / eə(r) /

UK / er /

A1
  • noun
  • Mixture of gases around the earth that we breathe
  • A person's manner intended to impress others
  • verb
  • To expose to the outside, to dry or freshen
  • To broadcast a TV or radio show
  • To open a subject to discussion and debate

propagate

Copy vocabulary

US / 'prɒpəɡeɪt /

UK / ˈprɑpəˌɡet /

B2
  • verb
  • To make an idea known by many people
  • To make new plants from parts of another one

real

Copy vocabulary

US / rɪəl /

UK / ˈriəl, ril /

A1
  • adjecitve
  • Actually existing or happening, not imagined
  • Being important or special

investigate

Copy vocabulary

US / ɪn'vestɪɡeɪt /

UK / ɪnˈvɛstɪˌɡet /

A2
  • verb
  • To try to find out facts; to carry out research

keep

Copy vocabulary

US / ki:p /

UK / kip /

A1
  • noun
  • Large, strong tower in the middle of a castle
  • Money spent on you so you can live in a place
  • verb
  • To continue doing something; not to stop
  • To stop balls going in a goal in sports
  • To not give back or return something
  • (Of food) to not spoil or not rot
  • To take possession of something to own, e.g. a pet
  • To have and continue to hold something
  • To do something that you have promised or agreed
  • To stay in a certain place or condition
  • To maintain the rules

something

Copy vocabulary

US / ˈsʌmθɪŋ /

UK / ˈsʌmθɪŋ /

A1
  • adverb
  • In some degree or measure
  • noun
  • a person or thing of some value or consequence
  • pronoun
  • Thing that is not yet known or named
  • Approximately

affect

Copy vocabulary

US / ə'fekt /

UK / əˈfɛkt /

A2
  • verb
  • To cause a change in something else

front

Copy vocabulary

US / frʌnt /

UK / frʌnt /

A1
  • adjecitve
  • Opposite of back; the forward part of an object
  • noun
  • Behavior not showing a person's true feelings
  • Area where fighting in a war is happening
  • Place where air of different temperatures meets
  • verb
  • To have the forward part facing something
  • To lead a group of people, usually a band

golf

Copy vocabulary

US / ɡɒlf /

UK / ɡɑlf, ɡɔlf /

A2
  • noun
  • Game played to hit a ball into a hole with a stick
  • verb
  • To play golf

normally

Copy vocabulary

US / ˈnɔ:məli /

UK / ˈnɔːrməli /

B1
  • adverb
  • In the manner that is usual or ordinary

only

Copy vocabulary

US / ˈəunli /

UK / ˈonli /

A1
  • adverb
  • Just one; just that amount or thing; not more than
  • Not very important or serious
  • Just that type of thing, person
  • Short time ago; not before a certain time
  • conjunction
  • Except; but

and

Copy vocabulary

US / ənd /

UK / ənd, ən,ænd /

A1
  • conjunction
  • Used to refer to two or more things
  • Plus; in addition; on top of that
  • Used to introduce an action that follows another

back

Copy vocabulary

US / bæk /

UK / bæk /

A1
  • adjecitve
  • Farthest from the front e.g. in a classroom
  • adverb
  • Have returned to a place you were before
  • noun
  • The part of a chair that the upper body leans upon
  • Location at the rear of something
  • The reverse of side something
  • Area on the rear of your body
  • verb
  • To bet money on something
  • To go backwards in a car
  • To support and encourage someone or some cause

guy

Copy vocabulary

US / ɡaɪ /

UK / ɡaɪ /

A1
  • noun
  • Man; boy; any person

from

Copy vocabulary

US / frəm /

UK / frʌm, frɑm,frəm /

A1
  • preposition
  • Starting at a particular place, time or level

out

Copy vocabulary

US / aʊt /

UK / aʊt /

A1
  • adverb
  • No longer stylish (e.g. fashion)
  • Away from home, business, or the usual place
  • In a direction/movement away from inside or center
  • noun
  • Act when a batter cannot continue playing
  • verb
  • To tell people a secret
  • Subtitles section
  • So I'm back at the University of Sydney with Rod Cross.
  • Hi Derek.
  • And today we're talking about the effects of air on projectiles.
  • We are.
  • Now normally we neglect these effects.
  • When I'm teaching students about projectiles, I tell them, forget about the air, let's just talk about gravity.
  • Because it simplifies the problem, but air is real, it's heavy stuff, and it affects the flight of all projectiles.
  • Alright, well, why don't we do a little experiment to show the effect that air can have.
  • This is a surprising experiment that we've set up here.
  • First of all, I'll show you what happens to a tennis ball when it rolls down this inclined ramp.
  • Well, that falls exactly like I would expect, basically a parabolic path.
  • As predicted.
  • But let's try something a little bit lighter, such as this paper cylinder.
  • It weighs only a gram or so.
  • The effect of the air will be more important.
  • Watch what happens this time.
  • Whoa!
  • So the paper cylinder goes backwards.
  • That doesn't make any sense.
  • I mean, it was rolling forwards off that ramp.
  • No, it does it every time, and it's because of an effect known as the Magnus force that's acting on the spinning cylinder, acts on a spinning ball as well.
  • And people who play sport know about it, but they wouldn't call it a Magnus force.
  • Why is it called the Magnus force?
  • Because Magnus was the first guy who discovered it when he was investigating why cannonballs curve as they propagate through the air.
  • Uh-huh.
  • And so what did he find out?
  • What he found is that when a ball or any object is spinning like this, there's a force perpendicular to the spin axis.
  • If it's spinning clockwise or with topspin, the force is down.
  • If it's spinning anticlockwise, counterclockwise, the force is up.
  • So how do we get a Magnus force on a ball?
  • As the ball's moving forward through the air, if it's spinning, the air is flowing around the ball from the front to the back.
  • The ball is spinning in the same direction as the airflow at the top of the ball, but in the opposite direction at the bottom.
  • Because of friction between the air and the ball surface, air is dragged around the top of the ball downwards towards the back, but at the bottom of the ball, the airflow and the ball are opposite directions.
  • The air comes to a screeching halt fairly soon instead of being deflected upwards.
  • The net result is air is deflected downwards.
  • Due to Newton's third law, the air exerts an equal opposite force on the ball, which is upwards.
  • So how would sports players take advantage of the Magnus force?
  • They make the ball curve through the air by a different amount than that due to gravity alone.
  • So a golfer will strike a golf ball with backspin.
  • That exerts a vertical force, a lift force on the ball that keeps it in the air for a longer time, and therefore it travels further.
  • A tennis player will hit the ball with topspin.
  • That causes the ball to curve down onto the court after it passes the net.
  • A baseball or cricket player will also do that.
  • But in addition, they can make a ball curve about a vertical axis, in which case the ball will either curve to the left or to the right away from the batter.
  • Making it much more difficult to hit the ball.
  • That's the object of the exercise.
  • I see.
  • So are there any other air effects that we need to be aware of?
  • There's quite a few, actually.
  • There's the buoyant force acting on a balloon, for example, or any object.
  • There's a drag force acting backwards that slows the ball down.
  • And if the ball happens to have seams, then there's a side force acting on the ball.
  • Aha.
  • Well, that sounds like a whole other episode.
  • That is.
  • Balls with seams.
  • That is.
  • All right.
  • Well, stay tuned if you want to find out how air affects balls with seams.