Yo-yo in vertical circle example | Centripetal force and gravitation | Physics | Khan Academy

[@MrMalucoxx]

Great video. There's just a problem when you consider that the velocity is equal everywhere, which is impossible because gravitation is accelerating the yo-yo. In accelerated systems like this, the centripetal force changes due to velocity and this change is necessary in order to maintain the circle. To calculate the last tension you would use first the law of conservation of energy to get the velocity and then the calculation in the video (it's valid since the expression of centripetal force is valid for all possible circular motions, in that instant)

[@AdityaSathya]

This is correct

[@sathibabu9365]

The luckiest person on the earth is David sir because he can tackle the physics very easy

[@urunclesam1659]

I’ve been confused for hours as to why mg was positive in my practice problems even when it was pointing down and you just relieved me for my test by 100000 percent thank you for existing :)))

[@wyattfelipe1458]

You all prolly dont care but does anybody know a tool to log back into an instagram account..? I stupidly forgot my account password. I appreciate any tricks you can give me.

[@clarisaleu-rodriguez5314]

Thank you! You're explanations are so clear and easy to follow.

[@asiyafatima544]

You guys are amazing at explanation !!! Khan academy , you people have helped me a lot in simplifying the concepts and making studies much easier ...

[@tk006]

I'm in high school currently and want to study astrophysics once I leave. My teacher said this topic will be very useful later on when we look at planetary motion so I want to understand it really well. This video condensed the information I needed perfectly.

[@karsnogen8141]

Thanks, i really need to do my homework now

[@jeffreytebbens3100]

Consider posting an example where the yo-yo is not at the top, but say, 45 degrees from the vertical.

[@trash5694]

Amazing explanation! Thank you so much

[@foureyedcyclopse9412]

Thank you. Very informative and helpful!

[@joshuamoodley7600]

Yoh! you just saved me from a really bad semester test in a few hours Thank you!

[@Learner2500]

U guys are the best thank you

[@nostyx_x]

Thank you sooooo much!!

[@azimbagwan2762]

physics is become easy due to you

[@anushreesabnis5856]

The velocity increases as the yo-yo reaches the downward curve of it's motion, doesn't it?

[@whatamitalkingabout3]

a video in which the yo yo was not at the top bottom rightmost or leftmost point would be very beneficial. probably wont be this easy on any test

[@saramehravar]

Thank You! Great Great Great Explanation

[@wongshanyan1724]

Question , the speed when the string snaps ?

[@nagysadaka7149]

Why we consider that the speed is constant but T is variable during the rotation ?

[@JRay2113]

Sooo clear!! thank you

[@tanveerfaridi7481]

thank u very very much sir it is very helpful for me

[@alevelsdemystified3410]

Great explanation!

[@mimamod1867]

I like how everything is in metric system. :D

[@danielkwon3062]

isnt there normal force on spinning yoyo? like ferris wheel problems?

[@olivetom1599]

And so we can say that earth gravity doesn't change it's impact on the string (and so on the finger) whatever the speed of the yoyo is. (and it's not that intuitive to me)

[@jameschen3138]

I calculated the Centripetal force as mv^2 / r = 8N. Is the centripetal force different from the tension force in this scenario?

[@vivialord5260]

thanks

[@jubairtayib8312]

wrong hey.... the velocity should not be the same in the lowest point...mg*2r + .5mu*u = .5mv*v . i think it should be like that ..... that means tension at every point T not only depends on the component of mg along the string but also depends on the velocity at every point as it will be changed because of gravity.

[@ahmedak_1]

Thanks!, very helpful.....:)

[@marwangoesfit6398]

isn't the centripetal acceleration formula only supposed to work when the object is in uniform circular motion?

[@ezraberger6912]

Ropes can't push

[@Dewayneyork1]

So in a since, the string is performing as a sort of artificial gravitational pull. Am I correct?

[@lilmarshmallow2204]

i didn't get the last part. how did the formula end up like that?

[@perveshikamonga4205]

can we calculate time period in this case...if yes, how??

[@goodboymzobe6460]

Is the velocity at the top equal to the velocity at the bottom?

[@thasleenathasli6210]

Can it explains by centrifugal force? ?

[@bezpeglar4134]

he sounds like Owen Wilson :P

[@adampaolillo1141]

Why is tension not equal in magnitude to mg??

[@aman2426]

Helpful (Y)

[@erererpo]

What application did you use here

[@devenarya5766]

i also wanna know that same... thnx for asking

[@nugget9245]

So what happened to the normal force?

[@clarisaleu-rodriguez5314]

There is no normal force

[@mihotsubaki8892]

Snowball9245 normal force is the force a surface exerts back on the object and there is no surface here.

[@joshuahamilton2833]

Snowball9245 this example is spinning vertically

[@jesusibarra5498]

Wouldn't the velocity be different at the bottom of the circle? So the answer should be different. Im having trouble finding out how to find the difference in velocity.

[@daleenhammoud623]

These problems deal with uniform circular motion, where the circular motion occurs at a constant speed; there is only acceleration because the direction of velocity is changing, but the magnitude (speed) is always constant.

[@SunilKumar-zs5vh]

@@daleenhammoud623 magnitude of velocity is changing brother it is non uniform circular motion ..

[@YahiaDesigner]

Why is the force of gravity always positive? doesn't it change direction when the yoyo goes around the circle?

[@dhavishsinghbissessur5004]

Foxy nope force of gravity is a constant. if gravaity is negative then things will start floating and mass will decomposit.

[@User-ei2kw]

bro

[@PokeShadow77]

This guy is even better than Salman Khan

[@tyrafero8590]

what about on sideways!!!

[@rofiqel6226]

I think when it's sideways you'd need to use trig

[@fsn1749]

tomorrow’s my physics test, god i just hope i pass 😭

[@Zazmo_]

Hope you did well :)

[@goranjaaf3199]

For all you atheists out there, behold God himself!!

[@mohamedgamal7600]

that is so confusing why didn't use f = ma and then break down f which the net force by seeing the forces and that is it , you are so confusing

[@willsonbasyal7883]

Tbh, I did not enjoy the explanation!

[@swagatmalla6634]

Willson Basyal dai which part? I actually understood what was going on.