Introduction to work and energy | Work and energy | Physics | Khan Academy
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Introduction to work and energy. Created by Sal Khan.
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Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy is a nonprofit with a mission to provide a free, world-class education for anyone, anywhere. We believe learners of all ages should have unlimited access to free educational content they can master at their own pace. We use intelligent software, deep data analytics and intuitive user interfaces to help students and teachers around the world. Our resources cover preschool through early college education, including math, biology, chemistry, physics, economics, finance, history, grammar and more. We offer free personalized SAT test prep in partnership with the test developer, the College Board. Khan Academy has been translated into dozens of languages, and 100 million people use our platform worldwide every year. For more information, visit www.khanacademy.org, join us on Facebook or follow us on Twitter at @khanacademy. And remember, you can learn anything.
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Stop reading the comments and pay attention to the lesson.
Thames .............
Lol thanks
Thames 😂
HAHAHA i'm reading comments while Listening. Now I realized that I need to pay Attention. Thanks for advice😂
Thames ty
Khan Academy - "looked it up on Wikipedia".
LMFAO!! Exactly what I was thinking
special
So?
May the Force be with you.
I approve this
I love my work too much buddy
may the force be with you
may the force be with you
no way... today is may the fourth
Sir, I owe you so much. You have been my professor through out most of my math classes.
Thanks
Title: "introduction to work and energy"
Khan: "I'm not gonna introduce you to the concept of work and energy"
now*
He said “NOW”
Please continue making videos, even for old topics. I always look back at all your physics videos every month to just revise myself and every time it helps a lot more than it did the first time.
Ancient Comment Acquired 😱
Why are u doing nowdays..?
@@dhruvchaudhary8054 👆
Very clear descriptions here that have really helped the students I teach. Thanks.
I have exam today,I hope I'm not gonna fail
Marco Polo Abenes how did ur exam go? I have mine tomorrow and am scared.
My physics exam is tomorrow and I am too scared.😓
hey bro,did you pass?
Abdelrahman Ashraff
Passing marks were 32 and I scored 32.😁😁
Tanay Gupta wow congrats bro Khan really save a lot of ppl
jesus, this came out in 2008 yet he has a better mic than most tutorials in present day youtube
ong
"Now, I want you guys to have the most accurate definition available so I just brought them from wikipedia"
Wait WHATT???
lol
+Nam Chanachon Late reply but it was a joke .
Wikipedia's definitions for the sciences and mathematics are pretty spot on, they actually often far more rigorous than the average student requires.
No that's a horrible misconception. Wikipedia is absolute trash and you should NEVER trust the information there because anyone can edit it. You can always just check the answer to that math or science problem on different, more accurate sources.
EveryExperience-A-Lesson that is not my point. If you're using Wikipedia as your only resource then yes, you are a moron, but that is not its purpose. it's supplementary material. A good example would be the definition of a rational no.
Its too sad that TH-cam has many easy examples but when my teacher asks a word problem that is hard, i can't find any solution to look for in youtube ☹️
how r u now ? u r in 10 th
You are right
Thats cuz these examples are basics to help u get going.. if u cant answer the "tough" questions.. u dont understand the basics...
I am at UNI and I am learning some quite complicated physics. These videos have helped me a lot. It is the basics that you must know before thinking of a problem. Imagine it like this you can not write a story if you do not know how to write.
🤘🤘
You might be the best teacher that I've ever learned from. Thank you so much for your amazing ability to explain formulas!
You sir, have made me understand physics. This will help me on my final exam in 2 days :) Many thanks.
how did it go?
These videos are so helpful! Thanks!
Your videos on fluids saved my life. I wish you had videos on fluids with friction as well.
Thank you so much :)
Work= Force*displacement
Laughing Sküll workdone=force*displacementcostheta
@@rollmosses1351 r8
I am nothing but grateful ❤
these videos always help. they actually explain things well so you can understand it. not just tell you to memorize formulas
@8:40 mind. blown. second time taking physics 1 and i have never seen this relationship.
this helps so much, thank you.
Thank you for sharing your knowledge.
man, im relying on you and your videos now to pass my physics finals cause i have been skipping so much lectures at uni..
Dude.. did you pass 😢
@@musicaldarpan629 We don't know.... we might never know ;(
Did you pass?
Did you pass?whare are you now??
@@tofoo72 no we're going to figure this out, just keep checking every year
He is the only math/science teacher that i don't get annoyed by their voice. his voice is so nice!
Sir, a little question i would like to get answered.
Why were the concepts of Work and Energy developed ? Could you please provide me with some examples of scenarios where we can explain that scenario only with the help of Concept of 'Work and Energy'. A scenario which can exclusively be explained by the concept of 'Work and Energy' and no other concept of physics could explain it.
In physics, "work" is when a force applied to an object moves the object in the same direction as the force. If someone pushes against a wall, no work is done on the wall because it does not move. However, depressing a letter on a computer keyboard requires work.
I have an exam physics tomorrow and I hope I don't fail after watching that video 🙏🙏🙏
Tfd
I'm from Germany and trough you I understood so many complicated concepts picturally. Thank you for your effort, you are my favourite teacher on TH-cam!
I always defined work as the transfer of energy onto another surface.
😃😃😃🤘🏻
Anything that promotes learning is wonderful!
This is a great review for my physics exam. thanks a lot
How did you do on your exam?
I have a lot of ENERGY. But I just sit there on the couch. My parents come along and FORCE me to put that energy to WORK: I took out the garbage, mowed the lawn, and painted the porch.
C)No forces are doing work on the object
D)There are no vertical forces acting on the object.
Now if it is at a constant speed the net forces must equal zero and there is no acceleration. First off how does it move if something is pushing and pulling on it with the same force? Second, my book says there is work being done by pushing and going against (friction), how is there work being done if the net force is zero? Thanks and blessings :)
Which video explains the equation at 5:33?
I like your videos and It is answering all my questions. Thank you.
Adam Caith the comment is over 11 years 😱
Very thank you sir for delivering such a nice lecture .. helped me very mich .. cleared all my queries
Ohh I saw about this guy on CNN Student News...thanks a lot for what you're doing! It's really inspiring and you make wayy more sense than my science teacher :D
10 year old 😳😅 amazing
This guy should be a millionare, he is so helpful and smart, Thank you!!!!!!!!!!!!!
Energy is what makes time and work possible. Work is an isolated event in which excess energy affects both the source of the abundant energy as well as the object that received some of the abundant energy
+Al Gi And do you believe most people would understand it? Much easier to write than speak sir.
I have an unreal imagination
Love your caption So much! It completely solve my language problem
thank you 4 the good work sal...
KE should apply at any angle, because a force can move an object, with any angle to the horizontal. In this example, the vector F not moving at any angle, but parallel to the x-axis, so theta would be 0. Cos(0)=1. KE=(1/2)(mv^2)(1).
I just want to let you know that I am taking Physics 1111 at the University of Georgia and I find your videos not only informative but VERY entertaining. Thanks!
Michael Gunter hi there
Oldest comment here 😳👀
thank u soo much for explaining this it was very informative
@Guffington It can't be a bit confusing especially since most energy is related to the motion of particles. Thermal energy is related the motion of atoms. However radiant energy doesn't relate to particles in that way. In fact, the Large Hadron Collider (LHC) collides atoms and destroys them, when you destroy atoms you release pure energy...there is no particle left. In fact, sometimes weird things happen and particles are created from energy (so "out of thin air" by the way we would see it)
this guys the man. makes it so much easier
10 years ago 😳👀
yes it is! infact that connention helped me score pretty well on my physics paper!
Work is energy in transfer. For a definition less circular
Deriving (Vf^2*m)/2 from f*d blew my mind. Wow. Awesome video and I love your sense of humor!
This is the most helpful thing I have ever watched on TH-cam!! Thank you so much!!
13 years ago... nice
can u guys believe that this video was posted on 17-02-*2008*
firkkin 13 years, many of us did not even reach this level of physics,
stop reading the comments and pay attention lol
I don't get the weirdo's who dislike his video.....Guess it proves that n matter how awesome u r u can't please everyone cause people have a tendency to be jealous idiots -.-
so useful 👍
*Why is this video 240p? I know that this is just a first world problem, but aren't the videos usually 720p?*
The Real EEED Cure is over 300 Yеars Old! twitter.com/aa553651fdb95b460/status/804602507225808896 Introduction to work and energy Work and energy Physics Khan Acaaaademy
thank you for that algebraic explenation to KE. Really helped :)
very much liked the derivation of kinetic energy formula
You are awesome dude! I was so desperate before i found your videos. Thank you very much.
my physics teacher is great, but this is a even better way of learning things!
Question: After Sal derived the equation to V = sqrt (2 (f*d/m); why did he bring the final V^2 back, and did not remain square-rooted?
when will you gonna use the angle theta?
😂😂😂😂😂😂lol
Is F the *resultant* force on the object, or exactly the force 'needed' to move the object? e.g.: I might 'need' only 1 N to move an object over 1 metre, but if I apply a 10 N force to that object over 1 metre, am I still doing the same work as if I applied a 1 N over the same 1 metre distance?
is there anything sal doesn't know?
I love Sal😀😆😊😍😍
Yah my name
Kinda late now, but think of it as a fraction: f/m times d/1 (because d has always been in the numerator) so it becomes fd/m when multiplied
The future will be Khan Academy in every school
U lied bro... I am from future 😢
isn't work = force * displacement
instead of force * distance
?
Nah, work is the distance moved in the direction of force *not* displacement, because displacement is the net distance moved
@ Hamza Shihimy. Fg=Mass *Gravitation Acceleration. Ex 2kg*9.81m/s^2=19.62 N.
I really love Khan, but Wikipedia isn't really a good source. Well, just sayin. Though, Khan is great! It really helps me a lot!
good way of learning things. this could help me 4 science homework!
14 people couldn't understand how great khanacademy is...
Now 300 😃😅
Wow well understood OmG I read this tins so many time I'm just understanding it right nw thank God
you are best than my teacher your way of teaching is really good
YOU SIR ARE AN ANGEL.
😆🤣 lmao
Well understood
@Guffington no energy does exist... in fact light is a part of the radiant energy spectrum we can see. To clarify, radiowaves, microwaves, infrared light, the visible light, UV rays, x-rays, and Gamma rays (nuclear blast strength radiation) are all the same thing...that is radiant energy.
i really like this keep up the good work!
Great!
Nobody:
Literraly nobody:
Khan: I just found this from Wikipedia :)
I know
Haha
Stupaad
@@monissuri6803 heh
I have physics exam tmr If I pass I'll thank yall
thanku sir
I’m 12’ why am I learning this
I am also
Same.
😢😢😢
mannn ur going to help me alot im a senior taking physics and its confusing as hell
but sad part is you use radicals or w/e u call them when you do cos
GOT IT:P Could you give us some sample problems in which we can solve and then answering it after? I mean so that we could be more interactive.
Work is TRANSFER of enegy from DONOR to ACCEPTOR provided net momentum is also transferred. If no net momentum transferred then it is just heat and not work.
qualquan whats the point?
Thx so much!!! I have a physics midterm tomorrow!!!
So, am I right and saying that energy doesn't actually "exist" in the same way that light and matter exist? It is just a model to help measure velocities and motion?
my mind exploded at 8:01. thank you sir for your sneaky awesome explanations.
Thanks u Sir.my dought got cleared after seeing the video .
It's not exactly circular. Work is the transference of energy, whereas energy is a property of state. Hence, Objects A and B have some quantity of energy, while if A does work on B, the B gains energy and A loses it. Very close to circular though.
Wooow man that's just what i needed. Healthier than a cup of coffee ;)
Hi Khan or anyone who can help I'm very annoyed right now I seemed to understand Physics very well when I took the course but am having a little trouble as I am studying for the Mcat. Anyways I have this question
An object with a mass of 50 kg moves across a level surface with a constant speed of 15m/s. Kinetic friction=.7 which of the following is true.
A)The force exerted on the object by kinetic friction is negligible.
B) There must be some other horizontal force acting on the object.
Thanks alot! You made it way easier for me :D SUBSCRIBED!
Run right through him with your arm forward with fist.
Power and Force are as fast as you run. 0 to 1 to 2 to 3 to 4 to 5 to 6 to 7 to 8 miles per hour (so x times). So the faster you run the more power and force you have. Go Girls!
let me define work for you, In physics, a force is said to do work if, when acting, there is a displacement of the point of application in the direction of the force.
thank you!
Oldest comment here 😳👀
What are you doing nowadays 😅
I get something unusual if I put the first two definitions together... Energy :- The ability to transfer energy by force... Seriously?!!
Sai Kiran energy is the ability to do work and work is the energy transferred by force so energy is force
Lolz 995 , everything was fine until I saw your last words, hmm, no offence, but energy is not a force... When you apply force such that you're doing some work, the total work done is stored as the energy is what I would say...
Sai Kiran so what I get from you is that energy is inside objects and if we want to use the energy we need to use force and that force is work and what you said is that the total work done is energy but wasn’t energy already inside the object before we apply force to it?
Hmm, a straight answer would be yes... the energy was already inside the object, it would be better if we call it matter, in other terms, matter itself is condensed form of energy, this explains lotta things. When you do work, you are transferring some amount of energy from one particle to the other, in macro level.
How much energy is in the matter?, Huge amount, Huge? unimaginable amounts of energy is condensed in the matter... Einstein's equation gives the relation between energy and mass, E=Mc²..., 'c' is the speed of light, and when u square the value, if you can imagine the number, then you could imagine the energy condensed in matter..., this takes us back to the transfer of energy, energy is always inside the matter, and when you do work, the energy is transferred from one body to the other..., Huge reply right?
My previous reply was just an intuition...
wat
I love you!!! and your videos tooo!!!
😃😃😃
if we pull a box we are doing the work or the force?but where force "finds" the energy to transfer it to the box? i am completely confused...equations far far more easier to understand
You go from v"square"= 2 f/m d - then go to v = square root of 2 fd/m, how did it go from f/md to fd/m?
d is in the numerator not the denominator. 2 f/m d is the same as 2d (f/m) which is 2(fd/m).