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Slow sock on Lubricon VI | Forces and Newton's laws of motion | Physics | Khan Academy

Video vocabulary

think

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US / θɪŋk /

UK / θɪŋk /

A1
  • verb
  • To have an idea about something without certainty
  • To have an idea, opinion or belief about something

drift

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US / drɪft /

UK / drɪft /

B1
  • verb
  • (Of sand, etc.) to be blown into heaps by the wind
  • (Of boats) to move without purpose on water
  • To move or live without a purpose or goal
  • To move slowly or effortlessly in water or air

ancient

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US / 'eɪnʃənt /

UK / ˈenʃənt /

A2
  • adjecitve
  • Very old; having lived a very long time ago

another

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US / əˈnʌðə(r) /

UK / əˈnʌðɚ /

A1
  • adjecitve
  • One more, but not this
  • determiner
  • One more added
  • pronoun
  • One more (thing)

anything

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US / ˈeniθɪŋ /

UK / ˈɛniˌθɪŋ /

A1
  • pronoun
  • A thing of any kind

along

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US / əˈlɒŋ /

UK / əˈlɔ:ŋ /

A1
  • adverb
  • As a companion; taken with someone
  • preposition
  • At a point on a line

from

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US / frəm /

UK / frʌm, frɑm,frəm /

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

over

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US / 'əʊvə(r) /

UK / ˈovɚ /

A1
  • adverb
  • Finished; no longer happening
  • Towards the ground/away from a standing position
  • noun
  • A set of six consecutive balls bowled in cricket
  • other
  • Finished
  • preposition
  • Showing the relation when a thing is above another
  • On or covering something
  • Above or across something
  • More than you need
  • From one side to the other
  • In the direction of; toward

keep

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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

and

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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

call

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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

equator

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US / ɪ'kweɪtə(r) /

UK / ɪˈkwetɚ /

B1
  • noun
  • Geographical line at zero degrees latitude

picture

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US / 'pɪktʃə(r) /

UK / ˈpɪktʃɚ /

A1
  • noun
  • General situation or state of being
  • Mental image of what something is or looks like
  • Movie; film
  • Painting, drawing or photograph on paper or screen
  • verb
  • To understand or imagine something
  • To imagine someone or something in an image

all

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US / ɔ:l /

UK / ɔl /

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

glide

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US / ɡlaɪd /

UK / ɡlaɪd /

B1
  • verb
  • To move smoothly and quietly as if without effort
  • (Plane) to fly without using the engines

its

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US / ɪts /

UK / ɪts /

A1
  • adjecitve
  • Referring to or belonging to ‘it’
  • determiner
  • Of something; belonging or related to something
  • other
  • Possessive form of “it”

lonely

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US / ˈləʊnli /

UK / ˈloʊnli /

B2
  • adjecitve
  • Sad because apart from other people
  • Being far away and rarely visited by people

top

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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

space

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US / speɪs /

UK / spes /

A1
  • noun
  • Empty area kept for a specific reason, like a car
  • Empty area with nothing in it
  • Area in the sky where the stars are
  • Area between written words on a page
  • verb
  • To make a certain distance or time between

travel

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US / ˈtrævl /

UK / ˈtrævəl /

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

atom

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US / 'ætəm /

UK / ˈætəm /

B1
  • noun
  • Smallest bit that matter can be broken down into

very

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US / 'verɪ /

UK / ˈvɛri /

A1
  • adjecitve
  • Concerning a large degree or amount
  • adverb
  • A lot; much; many
  • Used to stress or emphasize a noun

act

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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

kilometre

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US / ˈkɪləmi:tə(r) /

UK / ˈkɪləmiːtər /

A1
  • noun
  • A metric unit of length equal to 1000 metres

look

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US / lʊk /

UK / lʊk /

A1
  • noun
  • Person's beauty or physical attractiveness
  • Particular style of dress, clothes, or appearance
  • The way someone, something appears to be
  • Act of searching for or examining something
  • verb
  • To appear to be; seem

direction

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US / də'rekʃn /

UK / dɪˈrɛkʃən, daɪ- /

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

regardless

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US / rɪˈgɑ:dləs /

UK / rɪˈɡɑrdlɪs /

A2
  • adverb
  • Without being affected or concerned by something

eternity

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US / ɪ'tɜ:nətɪ /

UK / ɪˈtə:nɪti /

B2
  • noun
  • A very long time; forever

discover

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US / dɪˈskʌvə(r) /

UK / dɪˈskʌvɚ /

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

mass

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US / mæs /

UK / mæs /

B1
  • noun
  • Religious ceremony in some Christian churches
  • Large amount or number of something
  • Main or largest part of something
  • Large number of people considered as a whole
  • Amount of matter that an object has
  • verb
  • To gather people or things into a large group

per

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US / pə(r) /

UK / pɚ /

A2
  • preposition
  • In the manner directed or suggested
  • For each; during each

radially

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US / ˈreɪdiəli /

UK / ˈreɪdiəli /

C1
  • adverb
  • In a radial manner

such

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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)

just

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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)

die

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US / daɪ /

UK / daɪ /

A1
  • noun
  • Cube with dots numbering 1-6 on it used in games
  • verb
  • To cease to function or work
  • (Of a thing) to stop being used or done
  • (Of a person) to stop living

since

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US / sɪns /

UK / sɪns /

A1
  • adverb
  • At a point before the present time
  • conjunction
  • For this reason; because
  • preposition
  • From the time in the past that

for

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US / fə(r) /

UK / fɔr,fə /

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

time

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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

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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

special

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US / 'speʃl /

UK / ˈspɛʃəl /

A1
  • adjecitve
  • Being additional or extra
  • Different, better or greater than normal
  • noun
  • Heavily discounted sales item

earth

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US / ɜ:θ /

UK / ɚθ /

A1
  • noun
  • Wire connecting an electrical device to the ground
  • The planet we live on
  • Soil in which we grow plants

few

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US / fju: /

UK / fju /

A1
  • pronoun
  • Not many, a small number

strong

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US / strɒŋ /

UK / strɔŋ /

A1
  • adjecitve
  • (Of tea or beer) dark or thick
  • Having big muscles; physically powerful

friction

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US / ˈfrɪkʃn /

UK / ˈfrɪkʃən /

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

question

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US / 'kwestʃən /

UK / ˈkwɛstʃən /

A1
  • noun
  • Issue or problems you are dealing with
  • What you ask about; issue
  • verb
  • To ask for or try to get information
  • To have or express concerns or uncertainty

hour

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US / 'aʊə(r) /

UK / aʊr /

A1
  • noun
  • 60 minutes
  • Particular time of the day
  • Fixed, regularly occurring time

element

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US / 'elɪmənt /

UK / ˈɛləmənt /

A2
  • noun
  • Essential or particular part of something

directly

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US / dəˈrektli /

UK / dɪˈrɛktli, daɪ- /

A2
  • adverb
  • In a frank and honest way
  • Right away; immediately

first

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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

right

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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

block

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US / blɒk /

UK / blɑk /

A2
  • noun
  • Solid piece of material used for building
  • A piece of wood, chocolate etc.
  • Hard piece of wood, stone etc. with straight edges
  • Building made up of offices or apartments
  • Area of a city divided by four streets
  • verb
  • To stop from going forward or making progress

force

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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

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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

about

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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)

absolute

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US / ˈæbsəlu:t /

UK / ˈæbsəˌlut /

A2
  • adjecitve
  • Complete; total; pure; not limited in any way
  • noun
  • Something that is complete, total, pure, certain

even

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US / 'i:vn /

UK / ˈivən /

A1
  • adjecitve
  • Being equal in influence, power, possibility etc.
  • Being divided equally or fairly
  • (Of teams/contest) with similar chances of success
  • Smooth, level, or regular
  • Can be divided by 2; ending in 2, 4, 6, 8, or 0
  • At a regular, equally steady manner
  • Remaining steady and unchanging
  • adverb
  • (When this is surprising) as well; too
  • (Used to compare two things/stress the difference)
  • verb
  • To make something level; to flatten
  • To make something equal

like

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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

that

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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

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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

absolutely

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US / ˈæbsəlu:tli /

UK / ˈæbsəˌlutli, ˌæbsəˈlutli /

A2
  • adverb
  • Completely; totally; very

hydrogen

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US / ˈhaɪdrədʒən /

UK / ˈhaɪdrədʒən /

B1
  • noun
  • Lightest of all chemical elements

nothing

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US / 'nʌθɪŋ /

UK / ˈnʌθɪŋ /

A1
  • noun
  • Item of little or no value, importance, interest
  • Number or value of zero
  • pronoun
  • Not anything, not a single thing

bizarre

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US / bɪˈzɑ:(r) /

UK / bɪˈzɑr /

B2
  • adjecitve
  • Odd or strange

happen

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US / 'hæpən /

UK / ˈhæpən /

A1
  • verb
  • To take place or occur

decelerate

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US / ˌdi:'seləreɪt /

UK / diˈsɛləˌret /

C2
  • verb
  • To go more slowly; to reduce speed

let

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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

material

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US / məˈtɪəriəl /

UK / məˈtɪriəl /

A2
  • adjecitve
  • Relevant; (of evidence) important or significant
  • Belonging to the world of physical things
  • noun
  • Cloth; fabric
  • Supplies or data needed to do a certain thing
  • Substance from which a thing is made of

the

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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

assumption

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US / ə'sʌmpʃn /

UK / əˈsʌmpʃən /

A2
  • noun
  • Something you believe to be so, but aren't sure of

other

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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

perfect

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US / 'pɜ:fɪkt /

UK / ˈpɚfɪkt /

A1
  • adjecitve
  • So good it cannot be improved
  • verb
  • To do something so well, it cannot be done better

one

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US / wʌn /

UK / wʌn /

A1
  • pronoun
  • You; we; people in general; someone
  • The thing or person previously referred to
  • adjecitve
  • Used to refer to people generally
  • Being a strong example of (something mentioned)
  • number
  • Number 1

across

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US / əˈkrɔs /

UK / əˈkrɔs,əˈkrɑs /

A1
  • adverb
  • Distance from one side to another
  • (Go) from one side to the other of something

this

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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

answer

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US / 'ɑ:nsə(r) /

UK / ˈænsɚ /

A1
  • noun
  • Reply to a question someone asks
  • Solution to a problem or test question
  • verb
  • To reply to a question someone asks
  • To solve a test question or a problem

surface

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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.

also

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US / 'ɔ:lsəʊ /

UK / ˈɔlso /

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

kind

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US / kaɪnd /

UK / kaɪnd /

A1
  • adjecitve
  • In a caring and helpful manner
  • friendly and considerate
  • noun
  • One type of thing

you

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US / jʊ /

UK / ju /

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

deep

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US / di:p /

UK / dip /

A1
  • adjecitve
  • Complex and important
  • Extreme or intense
  • Going far down from the surface
  • Low in pitch, as a sound
  • adverb
  • At a certain distance beneath the surface

frozen

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US / 'frəʊzn /

UK / ˈfroʊzn /

A2
  • adjecitve
  • Hard, solid because it is below zero degrees
  • verb
  • To store an item of food in a cold place
  • To make someone to not want to communicate
  • To stop moving and be still; stay the same

outside

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US / ˌaʊtˈsaɪd /

UK / aʊtˈsaɪd, ˈaʊtˌsaɪd /

A2
  • adverb
  • Beyond the limits or edges of some place, thing
  • noun
  • Area around or near something, such as a building
  • preposition
  • Beyond the limits or edges of some place, thing

make

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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

normal

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US / 'nɔ:ml /

UK / ˈnɔrməl /

A1
  • adjecitve
  • Standard or regular way of doing something
  • Having standard mental or physical ability, health

side

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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

reason

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US / 'ri:zn /

UK / ˈrizən /

A1
  • noun
  • Ability to think about facts and form a judgment
  • Explanation for why something occurred or was done
  • verb
  • To think and make conclusions in a logical manner

particle

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US / ˈpɑ:tɪkl /

UK / ˈpɑrtɪkəl /

B1
  • noun
  • Adverb or preposition that joins with a verb
  • Tiny piece or quantity of something

either

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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

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US / hɪə(r) /

UK / hɪr /

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

continue

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US / kən'tɪnju: /

UK / kənˈtɪnju /

A1
  • verb
  • To do something without stopping, or after pausing
  • To start doing again after a break, pause, or stop

should

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US / ʃʊd /

UK / ʃʊd /

A1
  • other
  • Used to indicate what is proper or reasonable

actually

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US / ˈæktʃuəli /

UK / ˈæktʃuəli /

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

use

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US / ju:s /

UK / ju:s /

A1
  • noun
  • Ability to employ something
  • Need to enable it to work
  • Permission to do something with something
  • Act of spending money
  • Operation of a machine for its function
  • verb
  • To have; to eat, drink, consume etc.
  • To need to operate or work
  • To operate a machine, e.g. a computer
  • To treat a person badly
  • To do something with, for a task or purpose

net

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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

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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

gravity

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US / ˈgrævəti /

UK / ˈɡrævɪti /

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

outward

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US / ˈaʊtwəd /

UK / ˈaʊtwəd /

B1
  • adjecitve
  • Going away from a place that will be returned to
  • Seeming to be from the outside
  • Concerning how something appears on the outside

scale

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US / skeɪl /

UK / skel /

A2
  • noun
  • Size, level, or amount when compared
  • Small hard plates that cover the body of fish
  • Device that is used to weigh a person or thing
  • Range of numbers from the lowest to the highest
  • Dimensions or size of something
  • verb
  • To change the size of but keep the proportions
  • To climb something large (e.g. a mountain)
  • To remove the scales of a fish

whether

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US / ˈweðə(r) /

UK / ˈhwɛðɚ, ˈwɛð- /

A1
  • conjunction
  • If something will happen or not

can

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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

towards

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US / tə'wɔ:dz /

UK / 'təuədz, twɔ:dz /

A1
  • preposition
  • In the direction of someone or something

not

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US / nɒt /

UK / nɑt /

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

maybe

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US / ˈmeɪbi /

UK / ˈmebi /

A1
  • adverb
  • Possibly but not certainly; perhaps

our

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US / 'aʊə(r) /

UK / aʊr /

A1
  • determiner
  • Belonging to us

address

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US / ə'dres /

UK / əˈdrɛs /

A1
  • noun
  • Exact street location of a place
  • A formal speech to a group of people
  • verb
  • To write the place someone lives on a letter
  • To refer to someone or something formally
  • To make a formal speech to a group of people
  • To try to find a solution to; think about

really

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US / ˈri:əli /

UK / ˈriəˌli, ˈrili /

A1
  • adverb
  • Used to stress something that is said; definitely
  • In a true or accurate manner
  • Very

experience

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US / ɪk'spɪərɪəns /

UK / ɪkˈspɪriəns /

A1
  • noun
  • Thing a person has done or that happened to them
  • An event at which you learned something
  • Knowledge gained by living life, doing new things
  • verb
  • To gain knowledge by doing things

equal

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US / 'i:kwəl /

UK / ˈikwəl /

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

planet

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US / 'plænɪt /

UK / ˈplænɪt /

A2
  • noun
  • One of the bodies that orbit the sun

sock

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US / sɒk /

UK / sɑ:k /

A1
  • noun
  • Covering for your feet, worn under shoes
  • verb
  • To strike with your closed hand

video

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US / 'vɪdɪəʊ /

UK / ˈvɪdiˌo /

A2
  • adjecitve
  • Of a moving film, with sound
  • noun
  • Recording capturing action with sound
  • verb
  • To make a moving film of, with sound

yet

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US / jet /

UK / jɛt /

A1
  • adverb
  • At a later time (used after ‘not’)
  • (Used to emphasize that thing is, will be greater)
  • Eventually; at a future time
  • Until now; up to the present
  • conjunction
  • Adding to what has been said, often as a contrast

give

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US / ɡɪv /

UK / ɡɪv /

A1
  • noun
  • Degree of flexibility in something, a material
  • verb
  • To hand over or present something to someone
  • To cause someone to have or experience something

inward

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US / ˈɪnwəd /

UK / ˈɪnwərd /

B1
  • adverb
  • At the inside of

spiral

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US / 'spaɪrəl /

UK / ˈspaɪrəl /

B2
  • adjecitve
  • Curved in a continuous circle
  • noun
  • A continuous curve round a central point
  • verb
  • To move in a continuous curve round a point

star

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US / stɑ:(r) /

UK / stɑr /

A1
  • noun
  • Very famous person, usually an entertainer
  • Someone who does something very well
  • Your horoscope
  • A bright planet of hot gas in the night sky
  • A 5-6 sided asterisk-shape
  • verb
  • To perform or play a main role in a movie, play
  • To do something very well
  • To mark with a 5-6 sided asterisk-shape

air

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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

draw

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US / drɔ: /

UK / drɔ /

A1
  • noun
  • Something that attracts people to visit a place
  • A lottery or prize
  • Result of a game, contest where the score is equal
  • verb
  • To attract attention to someone or something
  • To get closer to or approach something or someone
  • To influence a person's involvement in something
  • To move an object by pulling
  • To create an image using pen or pencil and paper
  • To take one thing out of a container, etc.
  • (Of 2 teams) to finish a game with the same score

complete

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US / kəm'pli:t /

UK / kəmˈplit /

A1
  • adjecitve
  • Being finished; done; achieved
  • Being as perfect and as total as could be
  • verb
  • To finish or reach the end of doing something

could

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US / kəd /

UK / kʊd /

A1
  • other
  • Past form of 'can' to mean have ability
  • Used to ask for something politely, or to offer

know

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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

have

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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

part

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US / pɑ:t /

UK / pɑ:rt /

A1
  • adjecitve
  • To some degree; half; not fully
  • noun
  • Division of a book
  • Ratio of something, e.g. 3 of gin, 1 of tonic
  • A line in a person's hair, made with a comb
  • Character an actor plays on stage, movie, or TV
  • Some, but not all of a specific thing
  • Role in causing something to happen
  • verb
  • To make a line in a person's hair, by using a comb
  • To move two things apart creating a space
  • To leave someone, or to break off a relationship

tangential

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US / tænˈdʒenʃl /

UK / tænˈdʒɛnʃəl /

C1
  • adjecitve
  • Line of thought that is not related

without

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US / wɪˈðaʊt /

UK / wɪðˈaʊt, wɪθ- /

A1
  • preposition
  • Not with; not having

remote

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US / rɪ'məʊt /

UK / rɪˈmot /

A2
  • adjecitve
  • Being far away from people, towns, etc.
  • (Of a possibility) being small or not likely
  • (Of time) far off; long ago; far in the future
  • Not friendly; separating yourself from others
  • noun
  • Radio device designed to operate TV, etc.

away

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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

accelerate

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US / əkˈseləreɪt /

UK / ækˈsɛləˌret /

B1
  • verb
  • To cause to occur earlier than expected
  • To increase the speed or rate of something

orbit

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US / 'ɔ:bɪt /

UK / ˈɔrbɪt /

B2
  • noun
  • Path an object takes as it circles another object
  • verb
  • To go around another object (often in space)

with

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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

nor

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US / nɔ:(r) /

UK / nɔr /

A2
  • conjunction
  • Not this or that; also not

center

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US / 'sentə /

UK / ˈsɛntɚ /

A1
  • noun
  • Community place people go health or social reasons
  • Place in the middle of something
  • Person or thing that is attracting attention
  • verb
  • To direct focus toward something

ice

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US / aɪs /

UK / aɪs /

A1
  • noun
  • Frozen gas or liquid, esp. water
  • Sweet food made of frozen cream, or juices
  • verb
  • To make something cold by putting on frozen water
  • To spread a sweet and creamy substance on a cake
  • Subtitles section
  • This is a picture of the planet Lubricon-VI.
  • And Lubricon-VI is a very special planet because it's made up of a yet to be discovered element called Lubrica.
  • And Lubrica is special because if anything glides across the surface of Lubrica, it will experience absolutely no friction.
  • So if this right over here is a sheet of Lubrica-- we're looking at it from the side.
  • And if we have a brick on top of it, maybe gliding on top of it like that, it experiences absolutely no friction.
  • Now, the other things we know about Lubricon-VI is it's drifting in deep space and it does not have an atmosphere.
  • In fact, it is a complete vacuum outside of it.
  • It's in such deep space, such a remote part of space, that there aren't even a few hydrogen atoms right over here.
  • It is a complete, absolute vacuum.
  • And it's also an ancient planet.
  • The star that it used to orbit around has long since died away.
  • So it's just this lonely planet drifting in deep space without an atmosphere.
  • The other thing we know about Lubricon-VI is that it is a perfect sphere.
  • It is a perfect, perfect sphere.
  • Now, my question to you.
  • For some bizarre reason there happens to be, on the surface of Lubricon-VI-- so this right over here is the surface of Lubricon-VI.
  • There happens to be a sock that is frozen in a block of ice.
  • So this is my sock and its frozen in this block of ice.
  • And it happens to be traveling at 1 kilometer per hour in that direction.
  • If we were to look at it from this kind of macro scale when we're looking at the planet, let's say then that is the frozen sock, and it is traveling along the equator.
  • It is traveling along the equator of Lubricon-VI.
  • So my question to you, given all of the assumptions we made that it has absolutely no atmosphere, it's a perfect sphere, and Lubrica has absolutely no friction regardless of what's traveling on top of it-- what will happen to this frozen sock over time?
  • To answer that question, we need to think about all of the forces that are acting on this, I guess, frozen block of ice and sock.
  • And first of all, let's think about these forces that are acting in the radial direction, inward or outward, of the center of the planet.
  • Well, this planet has a mass.
  • And so you have an inward force towards the planet's center of mass.
  • And so you have the force of gravity acting on this block going radially inward to the center of the planet.
  • So I'll draw it like this.
  • So we have our force of gravity.
  • We have our force of gravity going radially inward, just like that.
  • But then we know that the block is not just spiraling towards the center of the earth.
  • We have the surface here.
  • It's not going to go through the surface of Lubrica.
  • We can also assume that Lubrica is a very, very, very strong material.
  • And so you also have a normal force.
  • You also have a normal force that is keeping the block from spiraling towards the center of the earth.
  • So this is a normal force.
  • And one thing we'll think about now, and we'll address it directly in another tutorial, is whether this normal force is equal to the force of gravity.
  • We'll think about that in a future video.
  • But these are all the forces that are acting in the radial direction, either inward towards the center of the planet or outward.
  • But if we think about in the tangential direction, along the surface of the planet, there are no net forces.
  • And because there are no net forces in this tangential direction right over here, this block will not either accelerate nor decelerate.
  • There is no air friction.
  • Or I should say air resistance, which is really just friction with the particles if you had an atmosphere.
  • It's a complete vacuum, so there's nothing there.
  • There is no friction with the surface of the planet.
  • So there's no friction there, which could have been a force in the tangential direction.
  • So there's absolutely no forces in the tangential direction.
  • So this block of ice will actually continue to travel at one kilometer per hour for all of eternity.
  • So it'll just continue to do it given the assumptions that we've just made.