I'm sorry, but you, sir, are amazing. I mean, jesus, you have every subject on your playlists created from your own time without getting any pay. What a selfless and sacrificial thing to do. Thank you so much, seriously. This is changing the world.
I wish more people were like Sal, who would care about other people so much, i.e. investing his own precious time in making these EXTREMELY useful free videos. So let's not be selfish and thank Sal by donating whatever we can, no matter how small or big it is! Thumbs up if you agree
Impulse is actually not measured in Joules. Joules are units of energy, not momentum. If you look at the equation for kinetic energy, KE = (1/2)*m*v^2, and do the unit analysis we get 1 j = 1 kg * (m/s)^2. Momentum and impulse share the same unit kg * m/s or equivalently N*s which can be found by analyzing the units of the momentum equation (p=m*v) or the impulse equation (J=F*t) respectively. Impulse and momentum unfortunately have no single simplified SI unit.
It's important to note, I think, that this is an example of a COMPLETELY INELASTIC COLLISION, because after contact, the two objects begin moving together as a unit as though they were stuck together.
Thank you! I find physics enjoyable and generally easy, but somehow, I've managed to not understand momentum. As we are really under pressure to get our course finished on time, I've fallen behind on momentum. So thanks for explaining it in great detail xD
you are amazing!@!!!!!! I understood what you were saying right away. Im not trying to be mean to my teacher in any way, but your teaching methods are far better. Thank you so much Khan!!!!!!!!!! BTW how do you write so well on your computer?
i have my yearlies next week, and i gave up on physics after half yearlies, but not started to study it agian but couldnt understand momentum and impulse HOWEVER NOW I DO :D thanks khan !
I have a very important 2 questions for me:) 1. In space, there is a space shuttle that does't move. Mass of this shuttle is always constant. This space shuttle has a rocket engine which produce a constant force of 100N. When the engine is started and the ship has a constant thrust of 100N, when the ship starts to accelerate, will the acceleration be constant and remain constant (let's assume 10m / s), or maybe the acceleration will start to decrease as the speed increases? It is related to the rule Ek = 1 / 2mv ^ 2 ??? 2. Same space shuttle doesnt move. Shuttle start to accelerate from 0km/h to 10km/h in 5 seconds and it takes "X" energy for example. How much energy it will needed to accelerate also 10km/h more in also in 5 seconds when it allready have velocity of 100km/h ? Also "X" energy? Or much more "X" of energy? And why is that?
Some basic definitions really, Momentum is a vector quantity, Kinetic energy is a scalar. As far as the equations go, p=mv , KE=1/2mv^2 Used together, they provide some very powerful insights in being able to describe the motion of an object.
in the "olden times", the word used instead of momentum used to be impetus, which came from the latin world petere (which stands for "to go towards/rush upon") and hence, the letter "p".
Lol, I've been watching these physics videos all day and got kind of bored, so I started messing around with the speed. Sal sounds so drunk when you set the video to .5x speed.
@shamiiix33 actually impulse is delta P or (triangle)P is what Sal writes. Impulse is the change in momentum, delta shows the change in the vector/scalar quantity. :)
Thanks for the help, this video really helped me a lot. My physics teacher is great, but explaining a problem and whatnot slows her down, yet you must be very quick to catch it and have good intuition to fathom it. Ironically, I had this same exact question on a test, and though I've presented an invalid answer, I'm glad to have finally understood this formula. I used to think it, (m1)(v1)=(m1)(m2), even with the knowledge of the formula you've shown. I was a bit doubtful... :/
Oh... my... god... I FINALLY UNDERSTAND WHY MOMENTUM IS CONSERVED. Thank-you so much. Your videos are so helpful. I watch them on my free time... that's sorta surprising.
So is anything in the universe truly instantaneous? Force takes a certain amount of time to act, when a ball hits a wall and rebounds, it is in contact with the wall for a certain amount of time.
Teagan Johner Except that it isn't. First of all, "a mountain" isn't a period of time. Even if it were, an avalanche wouldn't be "instantaneous" to it. Even when compared to the history of the earth itself, an avalanche still takes time to occur. Going back to the question, no, nothing is instantaneous. The closest thing would be the amount of time it takes for light to travel across, say, the width of an atom, but even that isn't. When we talk about "instantaneous" things, it is as if we were able to freeze time... That hypothetical freeze-frame is what we use to make instantaneous calculations, (velocity, accel., etc.)
The the initial mass of a body is = m1 The mass of the body changes to m2 At time t (the change occurs suddenly, as if m1 - m2 Was dropped on m1 at t ) V2 = m1V1 / m2 According to conservation of Linear momentum m1V1 = m2V2 But according to conservation of kinetic energy ½ m1V^21=½ m2V^22 V2 = V1_/m2 / m2 But velocity cannot be different.. So is one of the principals not applicable in here?
I didn't know Reggie Watts was a Physics whiz, too! What can't the man do? Seriously, though. Awesome video. Would have helped if I'd watched this BEFORE my last test. Momentum is way too easy to have missed out on 35/100 points.
Momentum is the real mv=p
you sir is so creative
Militant Pacifist this is how I'll remember it from now on :)
Omg this will surely help me, thanks :)
guys its not even hard to remember its just mass times velocity lol
Thanks! That will help me remember it come test time
This is 2020, I can't believe how much this one guy continues to be a lifesaver for me
Hello from the future
@@taqiabbas6868 No one can see future.And being a Muslim you should not 🚫 talk like this ...
I have the same name as you
Thank you so much! My highschool physics teacher can't teach very well and this is just so easy to understand
Blaze1436 same I cant really relate
My Physics teacher didn't show up for half the year, and now tommorow is my exam and I am stuck
Same
are you alive now , do you still get notifs
@@001simp yes
I'm sorry, but you, sir, are amazing. I mean, jesus, you have every subject on your playlists created from your own time without getting any pay. What a selfless and sacrificial thing to do. Thank you so much, seriously. This is changing the world.
are you a professor now?
I wish more people were like Sal, who would care about other people so much, i.e. investing his own precious time in making these EXTREMELY useful free videos. So let's not be selfish and thank Sal by donating whatever we can, no matter how small or big it is! Thumbs up if you agree
1:17 "how unpleasant would it be to be hit by that object" LMAO
Why cant teachers explain like this??!
cuz students are chatting all the time and the teacher is too busy telling them to be quiet... at least that's how it works in my high school...
Because here is KHAN Academyyyyy
thats why someone founded khan academy, he was simply unique above them all
my physics c teacher relies completely on us self-studying because he barely knows the material himself. so THANK YOU!!
you posted this on my birthday! :) little did i know 7 years ago i was gonna be in AP physics
omg fr?cool!
The SI unit of impulse is Newton-second (N*s), and it is denoted as J. The unit of impulse is not jules.
this new object called a cartruck... oh sal
Impulse is actually not measured in Joules. Joules are units of energy, not momentum. If you look at the equation for kinetic energy, KE = (1/2)*m*v^2, and do the unit analysis we get 1 j = 1 kg * (m/s)^2. Momentum and impulse share the same unit kg * m/s or equivalently N*s which can be found by analyzing the units of the momentum equation (p=m*v) or the impulse equation (J=F*t) respectively. Impulse and momentum unfortunately have no single simplified SI unit.
Newtons Seconds
a common misconception when J is used as Impulse
Khan Academy has saved my grades more than once and this physics video only has 75,000 views?! More people have to learn of this site!!!
Sal, thank you so much. I've been a student of yours for over a year, and you have helped me immensely.
Would it be possible for these old videos to be replaced with new recordings? For the sake of visual/audio quality.
6years later: NOPE!
7years later: NOPE!
I was only 3 years old when this video was released. I'd have never ever thought it'll be this useful to me in future
Thank you from Colombia! you are the physics teacher I have never had the patience to listen to
Thank for the kind information. Regards.
aaaah thank you so so much :) i have a gcse exam soon and you have no idea how much of a confidence boost you have given me.
Sal, you have really changed my perceptions about Science! I wish all my teachers at school were your duplicates...that would be so much fun!
thank you, after 9 mins now I understand what I couldn't in 2 years. thanks :)
It's important to note, I think, that this is an example of a COMPLETELY INELASTIC COLLISION, because after contact, the two objects begin moving together as a unit as though they were stuck together.
u helped me more than my college professor...
Thank YOU!!
this is freaking awesome dude!
thank you. cleared my doubt.
Thanks a million! You are a godsend for many of us that have to deal with confused teachers and incomprehensible accents! Cheers
Thank you! I find physics enjoyable and generally easy, but somehow, I've managed to not understand momentum. As we are really under pressure to get our course finished on time, I've fallen behind on momentum. So thanks for explaining it in great detail xD
you are amazing!@!!!!!! I understood what you were saying right away. Im not trying to be mean to my teacher in any way, but your teaching methods are far better. Thank you so much Khan!!!!!!!!!! BTW how do you write so well on your computer?
Thanks this video was really helpful. Was this based on the conservation of momentum?
i have my yearlies next week, and i gave up on physics after half yearlies, but not started to study it agian but couldnt understand momentum and impulse
HOWEVER
NOW
I DO
:D
thanks khan !
These videos are honestly better than my textbook examples. Thank you so much
Makes so much sense. Thank you!
I have a very important 2 questions for me:)
1. In space, there is a space shuttle that does't move. Mass of this shuttle is always constant. This space shuttle has a rocket engine which produce a constant force of 100N. When the engine is started and the ship has a constant thrust of 100N, when the ship starts to accelerate, will the acceleration be constant and remain constant (let's assume 10m / s), or maybe the acceleration will start to decrease as the speed increases? It is related to the rule Ek = 1 / 2mv ^ 2 ???
2. Same space shuttle doesnt move. Shuttle start to accelerate from 0km/h to 10km/h in 5 seconds and it takes "X" energy for example. How much energy it will needed to accelerate also 10km/h more in also in 5 seconds when it allready have velocity of 100km/h ? Also "X" energy? Or much more "X" of energy? And why is that?
Sal Khan, the King of the Science
this helps me SO MUCH!!
Lots of help thanks!
Some basic definitions really, Momentum is a vector quantity, Kinetic energy is a scalar. As far as the equations go, p=mv , KE=1/2mv^2
Used together, they provide some very powerful insights in being able to describe the motion of an object.
Changing Momentum....this is very interesting.
Admit it. You either have homework or a test (probably both). And you've come to Sal Khan for advice. Come, sit with us.
this is really gr8. am glad i found it. thanks
we watched you in science and it really helped
thanks!! this helped me a lot!
in the "olden times", the word used instead of momentum used to be impetus, which came from the latin world petere (which stands for "to go towards/rush upon") and hence, the letter "p".
great job sal. its impressive that how you conceptualize and explain it..
khan academy please do remake of this!
U r great !!! so simple but so helpful better than any other tutorials !!!!!
thank you.your 10 min video helped me more than 2 weeks that my teacher did!
Thank you for making this lesson that we were trying to understand it for weeks in just 9 minutes
Thank you, you guys are amazing!
You are so helpful, I can't thank you enough!
Sal's drawing skills are next level
Lol, I've been watching these physics videos all day and got kind of bored, so I started messing around with the speed. Sal sounds so drunk when you set the video to .5x speed.
LOL
Lmao he actually does
hey you are lol dump lol donkey
He Actually does
He sounds like Baymax with low battery lmaooooo
Yes.
Elastic collision:
Momentum, total energy and kinetic energy are conserved.
Inelastic collision:
Momentum, total energy are conserved.
@shamiiix33 actually impulse is delta P or (triangle)P is what Sal writes. Impulse is the change in momentum, delta shows the change in the vector/scalar quantity. :)
THIS man is nice and smart i love it this video is the best
cartruck !! nice video , thank you very much !!
Thanks for the help, this video really helped me a lot. My physics teacher is great, but explaining a problem and whatnot slows her down, yet you must be very quick to catch it and have good intuition to fathom it. Ironically, I had this same exact question on a test, and though I've presented an invalid answer, I'm glad to have finally understood this formula. I used to think it, (m1)(v1)=(m1)(m2), even with the knowledge of the formula you've shown. I was a bit doubtful...
:/
Great video! It helped me a lot. Thank you very much.
omg. thanx alot. u make it so easy. gd job!!!
Thank You 😊! It will help a lot in my exam tomorrow!
Sal is such a boss.
Explanations were comprehensive.....
Oh... my... god... I FINALLY UNDERSTAND WHY MOMENTUM IS CONSERVED. Thank-you so much. Your videos are so helpful. I watch them on my free time... that's sorta surprising.
"This new vehicle called a cartruck."
I lol'd.
very nice man, you've made things pretty clear to me, keep it up!
Thank you so much !! I understood everything :)
I already knew all about momentum beforehand but after this video, it's a loooot clearer (:
smart and simple explanation!!!!!!!
definition of momentum: "how little would you like to be in the way of that object as it passes by"
Pretty useful, thanks!
So is anything in the universe truly instantaneous? Force takes a certain amount of time to act, when a ball hits a wall and rebounds, it is in contact with the wall for a certain amount of time.
All time is relative, an avalanche is instantaneous to a mountain.
Teagan Johner
Except that it isn't. First of all, "a mountain" isn't a period of time. Even if it were, an avalanche wouldn't be "instantaneous" to it. Even when compared to the history of the earth itself, an avalanche still takes time to occur.
Going back to the question, no, nothing is instantaneous. The closest thing would be the amount of time it takes for light to travel across, say, the width of an atom, but even that isn't. When we talk about "instantaneous" things, it is as if we were able to freeze time... That hypothetical freeze-frame is what we use to make instantaneous calculations, (velocity, accel., etc.)
Wow! You do physics videos too! I always used your videos to get me through math classes. What an amazing discovery!
u r the best..ur all tutorials are so helpful. thankyou so much😙😙
You are really awesome! You've just saved my life and my final exam :') I am just about to cry or something :D
Best tutor in the world
Best physics lesson ever
You should do a video about the coefficient of restitution.
3:28 joule? I thought it has the same units as momentum? Kg*m/s or N*s
smart and great explanation!!
thanks for the video. very useful. What is the black board sofware?
The the initial mass of a body is = m1
The mass of the body changes to m2 At time t (the change occurs suddenly, as if m1 - m2 Was dropped on m1 at t )
V2 = m1V1 / m2
According to conservation of Linear momentum m1V1 = m2V2
But according to conservation of kinetic energy ½ m1V^21=½ m2V^22
V2 = V1_/m2 / m2
But velocity cannot be different.. So is one of the principals not applicable in here?
Thats Awesome i have a life that i dont understand this , thanks god , finally , Khan Academy thanks !
just curious, what year level are you learning this at school? or how old are you when you got taught this?
the colors inverted omg.
impulse is J. and you showed us an inelastic collision with the car and truck. Thank you :)
I didn't know Reggie Watts was a Physics whiz, too! What can't the man do?
Seriously, though. Awesome video. Would have helped if I'd watched this BEFORE my last test. Momentum is way too easy to have missed out on 35/100 points.
Really helpful, this will definitely help me on my test tomorrow.
so...where are you now
thankyou its really helpful you deserve a like👍
Thank you so much! This was so helpful :)
Allakh pandey sir( physics wallah) please also make a video on impulse and impulsive force.
thank u sooooo much 4 making this video.
it helps a looooooot
FINALLY MAKES SENSE :D thankyouuuuuu
"this new vehicle called the cartruck" very nice
wait, will the new velocity be the square root of the initial velocity before momentum started, like for the car example?
thank you so much!
THANK YOU!!!!
Nice 👍 thank you
thank you very much
aweesomeee :)
lolz car-truck object. I'll remember this for May 17 when i have csec paper 2 exam. Damn your videos are saving my butt in physics and bio