Work example problems | Work and energy | Physics | Khan Academy

[@MrChickenspit]

im just spending my weekend learning this for my exam, and damn it makes sense now!

[@aquamamba7768]

yes because this video is great

[@moaiya8]

I just got mind blown by very specific explanation of a very simple question... It was so helpful.

[@aquamamba7768]

this is mid blowning video because this is a cool video

[@madibrischuk8210]

i'm the trashcan

[@aquamamba7768]

yes because your smell is bad

[@barzangharib6711]

Madi Brischuk slfkxwn C

[@cashoo7143]

😪😂😂

[@malaika5122]

Going through so much

[@SamanZeb-il9dc]

Lol

[@tomteptv6203]

at 3:34 i think the trashcan should be moving up with a constant velocity, so when we apply a force that has magnitude equal to the gravitational force, it will keep moving upward with a constant velocity, however, the trash can's velocity is 0 at the beginning, so it will not moving anywhere after the force is applied on it.

[@The2AmInventor]

Yeah thats what I was thinking too

[@TheTocoe]

Yes I agree, acceleration should be equal to gravity if it has constant velocity. But for the trashcan to have any velocity then acceleration would've been greater than gravity at some point.

[@faithfury2397]

i really recommend watching this video first before jumping to organic chemistry channel so much stuff happening there even if the video is labeled "basic introduction" it will still mess up your brain. i watched organic and then this, and it make so much sense now! if u want just to solve problems then go there but if you want to understand the principle, this video is much simpler.

[@daedra40]

More of this garbage please (that wasn't supposed to be insulting :P) love it!

[@aquamamba7768]

i love you too!

[@Iseeyou0165]

@@aquamamba7768 wtf lmao

[@affif330]

LMAO@@Iseeyou0165

[@aurora-sf8hd]

I love the background music, it make me more eager to learn and make me commpetitive

[@LeadwithaStory]

I love these explanations and videos. I just really wish they would remove all of the music. It's so distracting. It actually decreases the value and effectiveness of the video.

[@water6133]

*may the force be with you*

[@snehashahid07]

and that does make sense . Thanks man , after 10years

[@whig3982]

NOW IT MAKES A LOT OF SENSE!!!!!

[@aquamamba7768]

of course

[@مروانابورويشة-ح4ث]

so so so so wonderful, thanx u r amazing!!

[@SangeetaYadav-bl1cs]

I think to move trashcan up one has to apply a force greater than the mg , because if we apply same force there will not be any vertical displacement equal and opposite force will cancellout each other...am I right???

[@YakobWakjera]

I think he left that part out.....for another video

[@theadchefer]

love it but can you leave the music out in future videos... its a bit distracting

[@aquamamba7768]

its distracting because you want to be distracted

[@muhammedsanimuhammed6253]

In my own case and a commenter above d music motivate us

[@devdass.k2013]

helped a lot 🙌🙌🙌

[@mousaalsaeed9410]

but in the last case we have changing in potential energy is that mean that there are work done????

[@aquamamba7768]

its done because the work is done

[@allyb7792]

I came to the comments because I’m confused by the same thing. In one of their previous videos they do a similar example and show an increase in the potential energy... which should be work. If the force upwards on the trash can is exactly the same as the force of gravity pulling it down, and we started at rest, why would there be any movement. It went from 0 initial velocity to some velocity, so there should be a change?

[@anissagomez1956]

This helps me so much! Thank You!

[@aquamamba7768]

your welcome

[@ghislainenguetse2967]

Very very good bravo👏👏👏👏👏

[@kotosqoposrly]

You should have talked about the potential energy of the trash can when lifted instead of the kinetic one. But anyways .. thank you for this :)

[@aquamamba7768]

your welcome

nice video dude

[@TheGuywithnolife]

Thanks :)

[@ghislainenguetse2967]

Exactly 👊👊👌

[@davidortega3393]

The work formula is actually pretty analogous to actual work in life. If you apply an effort (ie. force) in your job, and make no progress (ie. distance), you really haven’t done any work…😂😢

[@devdass.k2013]

Thanks

[@tbaloni]

I’m confused in the last part how was there no work done when the trash can was lifted vertically? There was a change in displacement vertically but that doesn’t change the kenetic energy?

[@vijaysinghchauhan7079]

3:21 won't the final velocity be zero coz after some time the trashcan is gonna come to rest. However, if I use this reasonable intuition, my initional velocity come out to be an imiganary number... 😫😫

[@molli1027]

I think the pulling of trashcan is continous and we are only solving for the final velocity at the 10m distance travelled by the trash can. Only 11 months late to reply hehe

[@heezyyyy]

Bruhh khan academy explained work within just 5 mins

[@isaacsechslingloff1006]

If the net force is zero, the trash can shouldn't move unless it's already moving.

[@c7hu1hu]

Got me at "the trashcan is disgusting"

[@jmt9361]

Can you explain how you got the velocity Cause I still don’t understand how you got 10 out of nowhere

[@thakichowdhury4482]

He just solved for v in the following equation 200J = (1/2)(4kg)v^2 i.e. 0) starting equation 200J = (1/2)(4kg)v^2 1) multiply both sides by 2 400J = (4kg)v^2 2) divide both sides by 4kg 100J/kg = v^2 3) finally, take the square root of both sides to isolate v √100J/kg = v 10m/s = v Joules can be thought of as kg(m^2/s^2) and is why dividing by kg and taking the square root leaves you with the velocity SI units of m/s.

[@BeneficialAttempt]

There is network on the trashcan!

[@xraykite1103]

how did you get 10?

[@chrisgloryson9899]

It is taken as an assumption bro

[@aquamamba7768]

because the answer is zero

[@homeplate9410]

Multiply 2 times 200J. Divide 400j by 4kg. Take the square root of 100. Answer is 10m/s

[@molli1027]

You should have showned that the mass of the trashcan is 4. I took me 23 secs to realize huhu

[@kavhein5674]

😂same

[@hyperbeam9545]

What's the formula

[@denswellforrest1539]

Savage_Khan "The Trash Can is Disgusting'

[@juangarza7561]

It's too fast I'm totally lost

[@sherazkhan2802]

Shouldn't we put the force in the first case as 20 N because 30 N will be cancelled by the opposing friction , so the net force will be 20 N .... but he put it 50 N !!! Why? And to lift the trashcane we should apply a force greater than 39.2 N isn't it ??

[@ruskodudesko9679]

lift the trashcan at constant velocity he said - so newtons first law, and third law states that those two forces must be equal for it to move at constant velocity, Fnet = Fa - Fg = 0 (newtons first law, where Fa is the applied for, and Fg is weight due to gravity) and then you can say Fa = Fg. so to move at constant velocity you need 39.2 N, any more and you will accelerate, and gain velocity. As for your other concern "Shouldn't we put the force in the first case as 20 N because 30 N will be cancelled by the opposing friction , so the net force will be 20 N .... but he put it 50 N !!! Why?" - because he didn't calculate the net force. Those are two separate forces, and you can get the net work by adding the work done by the tension force to the work done by the friction force. He didn't want net force, he wanted net work. Although you could just get the net force and use that to find the net work as well. There are two ways to do it. Work is in Joules, so the net work was 200J. You are correct in the net force is 20N, so 20N times the displacement 10m is also 200J, which equals the same value.

[@olivergaming723]

Im getting trouble on how is he getting the juels.

[@hassanahmad4417]

Hi

[@wncy1857]

+500J-300J+0+0 how did it become +200J?

[@sosygmingmc5030]

Because 500-300=200.

[@neetunagula1962]

I don't know trigonometry!😖

[@aquamamba7768]

cuz your a smart one

[@ruskodudesko9679]

sohcahtoa - take an angle, and the side it opens up to is the opposite, the side it touches it adjacent, and the hypotenuse is the longest side - this is for right triangles. let hypotenuse = c, then pythagoras proved that c^2 = a^2 + b^2, where a and b are the other two sides. if you solve for a side you get the cos(theta), in the equation. Learn trig it is invaluable.

[@ruskodudesko9679]

the trash can is disgusting - that is why they tie the string around it

[@user-bl6ni3yu4p]

I sexually identify as kilometers per second, because i really want to km/s.

[@olivergaming723]

I dont understand anything bruh

[@marichutesado180]

I lost it in 2:43

[@mahimmarufuzzaman3588]

Basically, the sum of all the work calculated. That's why its called "Worknet"

[@laughy38247357075834]

please without music next time. it's distracting and annoying

[@NC-vn4co]

Am I the only one who doesn't get anything 🙄😭

[@porras543]

BORRING

[@molli1027]

Nerds

[@viveks7496]

Very nice I liked it

[@MEWDISHA]

Thanks