Question

1. A disc and a sphere of same radius but different masses roll off on two inclined planes of the same altitude and length. which one of the two objects gets to the bottom of the plane first ?
a) sphere
b) both reach at the same time
c) depends on their masses
d) disc

Answer 1

Answer:

A) sphere reaches first

Explanation:

acceleration for any body rolling on an inclined plane is given by the expression

a=g.sin(ø)/[1+(I/MR^2)]

So the object with greater MoI will have lesser acceleration

Since MoI of disc= (MR^2)/2

MoI of sphere =2/5(MR^2)

MoI of disc>MoI of sphere

Acceleration of sphere> acceleration of disc

So sphere reaches first

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