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– [Instructor] Pretend

you are a physics student. You are just getting out of class. You were walking home when you remembered that there was a Galaxy

Wars marathon on tonight, so you’d do what every

physics student would do: run. You’re pretty motivated to get home, so say you start running

at six meters per second. Maybe it’s been a while

since the last time you ran, so you have to slow down a little bit to two meters per second. When you get a little

closer to home, you say: “No, Captain Antares wouldn’t give up “and I’m not giving up

either”, and you start running at eight meters per second

and you make it home just in time for the opening music. These numbers are values

of the instantaneous speed. The instantaneous speed

is the speed of an object at a particular moment in time. And if you include the

direction with that speed, you get the instantaneous velocity. In other words, eight meters

per second to the right was the instantaneously

velocity of this person at that particular moment in time. Note that this is different

from the average velocity. If your home was 1,000

meters away from school and it took you a total of

200 seconds to get there, your average velocity would

be five meters per second, which doesn’t necessarily equal

the instantaneous velocities at particular points on your trip. In other words, let’s

say you jogged 60 meters in a time of 15 seconds. During this time you were

speeding up and slowing down and changing your speed at every moment. Regardless of the speeding

up or slowing down that took place during this path, your average velocity’s

still just gonna be four meters per second to the right; or, if you like, positive

four meters per second. Say you wanted to know

the instantaneous velocity at a particular point in

time during this trip. In that case, you’d wanna

find a smaller displacement over a shorter time interval that’s centered at that

point where you’re trying to find the instantaneous velocity. This would give you a better value for the instantaneous velocity but

it still wouldn’t be perfect. In order to better zero-in on

the instantaneous velocity, we could choose an even

smaller displacement over that even shorter time interval. But we’re gonna run into a problem here because if you wanna find a perfect value for the instantaneous velocity, you’d have to take an

infinitesimally-small displacement divided by an infinitesimally-small

time interval. But that’s basically zero divided by zero, and for a long time no one

could make any sense of this. In fact, since defining motion

at a particular point in time seemed impossible, it made

some ancient Greeks question whether motion had any meaning at all. They wondered whether

motion was just an illusion. Eventually, Sir Isaac Newton developed a whole new way to do math that lets you figure out answers to

these types of questions. Today we call the math that

Newton invented calculus. So if you were to ask a physicist: “What’s the formula for the

instantaneous velocity?”, he or she would probably give you a formula that involves calculus. But, in case some of you

haven’t taken calculus yet, I’m gonna show you a few ways to find the instantaneous velocity

that don’t require the use of calculus. The first way is so simple

that it’s kind of obvious. If you’re lucky enough to have a case where the velocity of an

object doesn’t change, then the formula for average

velocity is just gonna give you the same number as the

instantaneous velocity at any point in time. If your velocity is changing, one way you can find the

instantaneous velocity is by looking at the motion

on an x-versus-t graph. The slope at any particular point on this position-versus-time graph is gonna equal the instantaneous velocity at that point in time because the slope is gonna give

the instantaneous rate at which x is changing

with respect to time. A third way to find the

instantaneous velocity is for another special case where

the acceleration is constant. If the acceleration is constant, you can use the Kinematic Formulas to find the instantaneous

velocity, v, at any time, t. (electronic music)

Design & Developed By ThemeShopy

Ahhh this is so good! Have been scratching my head at my textbook for 10 minutes about this concept and your video totally cleared things up. Thank you!

yeah! really,

you nailed it!

They din't teach us Calculus at school and began with this right away. Is it normal or it's the educational system here that's flawed?

This is really great!!! Thank you.

amazing video, one of the best of the khan academy(they do have awesome videos

)

Make and Edit to your Video on Sir Isaac Newton and Gottfried Wilhelm Leibniz being the inventors of calculus. (Thank you.)

What? What? What? Your statement is flawed? Newton was not the sole inventor of calculus! Lets not forget Gottfried Wilhelm Leibniz. And how is this not calculus, calculus is partly a series of statements that defines the gradient in a point as that is what you are discussing isn't it, also your first tip would be obvious (if you have the instantaneous velocity information then yes calculus becomes obsolete in use for calculating gradient on the first derivative, (which you could express the full story in a simple function from which the gradient could be calculated without using the whole graph of the information), its just perfect). Yes you could find the area under the graph using the principle of Cavalieri (might be nice to add this to your video/as a simplified method of doing what is done in calculus to find the area true not needed for instantaneous). But how else do you think it was figured out. Back to the original statement. Please add a message excusing your mistake of Newton being "the inventor of calculus" which precludes any other inventors. May I point out the Newton-Leibniz Controversy.

However, I must compliment you on your simple and fast explanation of the infinitesimal. Nice mentioning the ideas of the Zeno of Elea. But please add a small comment on Leibniz being included, it is important; and since you are catering to audiences that are possibly non-Britain or nationalistic to Britain. Wouldn't it make sense to include Leibniz, as they were the only side that were ever against Leibniz's calculus.

Blame the guy that sent me this video so I could start this statement. Sorry.

mann i would be a sicentist if you were my teacher i would love phyiscs as my mother

That was perfect.

I'm gonna to teach this forr my students lol

awesome !! very well explained 🙂

Is average speed synomous to velocity? I don't know.

Hu, what about Leibniz?

thanks!

This is amazing! I can't believe people also did this: "_

____wouldn't give up, so I'm not giving up either!"I want you as my teacher

Yo check out my mixtape

SoundCloud: BigFishStickBoi

How would I work out instantaneous accelleration using this same example?

What a Cool and Awesome Video.

Great Job!

FANTABULOUS!!!!!

Newton walks into the room of squabbling physicists: He picks up the mic.. "Calculus bitches.." – epic mic drop

this is what I got: for a very very very small interval of time "dt" the very very very small distance covered by object is "dx" then if object will continue motion for another 1 second of time than the distance covererd is the instantaneous velocity of the object.whereas for a time interval of t seconds the distance covered by object is d than distance covered in one second by the object is the average velocity of the object!! huh

THIS HELPED SO MUCH THANK YOU WHOEVER YOU ARE I LOVE YOU

Thankyou!

awesome

sir, suppose if velocity of a bullet reduced to half then what will be the situation of the acceleration ????

will it be remain same or it will also decrease ????

It's my fifth time and I am watching this cool shortly explained video! I am having a test tomorrow, so I wandered instead of reading my book and summarize this topic, why not look again at this video? Well! I did revise this whole bunch of complicated topic with just this video! Thanks a lot! 😜

I will watch this video again and again :-))

#Fantaboulous sir just explain limit why it approaches to zero….

Actually it was Liebniz that invented Calculus :^)

thanks so much

thank you sooooo muchhh…..

At last after four years, now i got the concept of instantaneous velocity. LOL

Bravo 4min & 38 seconds its all clear… Where as my teacher took 40 minutes but still….. Thanks

I thought that they collaborated with minute physics

Isn't 5m/s that it takes to go to your home that is distant 1000m and 200 seconds to take your average speed and not velocity since those values are scalar and no direction nor unit vector involved?

Thank you so much!!

cool accent 😀😁😁😁😝

WONDERFUL!!!!!!!!!

LOL at "pretend" you're a physics student. Like who else would be researching these videos beside mainly physics students?

I wish I could run at 24 m/s

Look the new formula for photon's energy on the SALEH THEORY group's youtube chanel:

Saleh Theory-com

let me save ur time. he starts teaching at 3:35. np

o didn't to lose but you kept me in save

THANK U HOOMAN

thanx

for this good video

sir

u clear all my doubt

thnk u sooooo much

So … the instantaneous velocity of an object can be

negativeduring a specific moment on a time interval, despite the average velocity being positive???same😂

nice video great and short explanation

4 minutes and 4 days….huge diff in this and my school

Very nice understanding skills ………plz tell instantaneous velocity in terms of circular motion

Awesome Boy 😀💖👍

Can any one solve this problem?

A car moves with a speed of 40 kmh^-1 for the first half time and with a speed of 60 km/h for the second half time. What is averge speed during while journy?

whats the name of the song that plays

Thank you sir

this beat lit

Thank youuu

Sir I can't understand graph

This was so easy, why dont teachers teach us like this..

this video makes me depressed do not rekamend

His explanation was very clear. Loved this video

What my teacher cant teach me in 4 hours inn 4 minutes

Ancient Greeks: The best Overthinkers

আমার চ্যানেলে পলিটেকনিকের ভিডিও আপলোড করা হয়ে থাকে

ⓦⓐⓣⓒⓗⓘⓝⓖ ⓣⓗⓘⓢ ⓕⓞⓡ ⓐⓝ ⓔⓧⓐⓜ ⓦⓘⓢⓗ ⓜⓔ ⓛⓤⓒⓚ😭😀😭😀

Awesome can you please upload instantaneous acceleration

i Wish I had a teacher Like him LOL

Great class

U r awesome man

I wish they didn't put background music into it. It's distracting and bothersome when playing at fast speeds. Please don't do this anymore. Keep with the khan methodology for videos. Thanks. Great work, but sh*t background music.

plz understand in hindi

Nice

Song?

I can’t understand anything

Who is captain antares???

great awesome keep it up keep going awesome video thanks alot

ok, now this is epic

that star wars analogy is too accurate

I would disagree with you [ at 2:47] when you say that 'an infinitesimally small distance/ an infinitesimally small time' = 0/0. NO IT DOESN'T!! An infinitesimally small distance STILL has a start point and an end point. An infinitesimally short time interval STILL has a start time and an end time, ie a duration. NEITHER of these quantities are zero therefore their ratio is NOT 0/0!!

someone just please kill me.

That. Was. Good.

Well will there be a speed when the time interval is zero ?

Well will there be a speed when the time interval is zero ?

Well enough but it didn't help me out.

Wow cool dude that was so simplified men kepp it up

really you are a great teacher

thank you

what a terrible physics student, he should be doing the massive amount of homework he obviously has, not watching tv or a movie

…he must be me

Shouldn't all the instantaneous velocities have +/- signs in front of them since they are vectors?

Shame to those 126 dislikes, this video was amazing, perfectly understood what I couldn't in a 2 hours class, Thanks for the amazing work.

The best Video at youtube on this topic

Thank you <3

lord, he ran at 28.8 kmph at the end

the motivation is real people

amazing 😉

and how this was easy in high school but now at college it’s hard ?

Wow thank you!! This is amazing!!

Spr

I need help to the calculus? Function, limit, graphic and instantaneous.👷🏻♂️

Amazing

Cleared up some points I 've struggled with. I'm glad I donate to Kahn Academy.