IIT JEE , AIEEE Forum - Physics , Mechanics

aditya.cool.guy.200031

so answer is b and not a.plz rate me.

Betu

nancy,

i'm afraid i can't think of any correct answer other than a).

i'm not being arrogant...but there could be a mistake.

i still think the correct answer is only a)..(Rolling can take place in inclined smooth surface..)...

any expert around..!!!!!!!

nancy_shrija

betu,

u say that on an incline, weight of the sphere would provide the torque.but what i think is that without friction rolling would not be possible.the weight would only help in sliding down and not in rotating.as it is the weight passes through centre of mass.so its torque about centre of mass would be zero.

so i say both (A) & (B) are right.but the answer is only (B).so i stand wrong somewhere.

if possible could u plzzz check another set of m c q of mine named as 'rotation based questions'?i have common conceptual problem in the 3 mcq.

i would surely rate u

Betu

My point was weight will provide the torque around point of contact .
Vertically downward weight through the centre of sphere won't pass through point of contact..hence it will be able to provide some torque.

your point that weight will not provide any torque about centre of mass is ok , and in fact torque about centre of sphere will be need for pure rolling ..but in our case it will be some sort of rotation -cum skidding motion...but sphere will turn some angle around point of contact and turning some angle is called rotation , i believe.

Pl also keep in mind this will not be pure rolling as point of contact is not at rest..in fact it is accelerating downward (skidding in fact)

More i think about it more i get convinced that it will roll (with skiddin , of course) on the inclined surface.

On the contrary ,on the horizontal smooth surface its weight can't provide any torque around the point of contact as weight passes through it...

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