Rotation 3 Question 4
10. A ball moves over a fixed track as shown in the figure. From $A$ to $B$ the ball rolls without slipping. If surface $B C$ is frictionless and $K _A, K _B$ and $K _C$ are kinetic energies of the ball at $A, B$ and $C$ respectively, then
$(2006,5$ M)
(a) $h _A>h _C ; K _B>K _C$
(b) $h _A>h _C ; K _C>K _A$
(c) $h _A=h _C ; K _B=K _C$
(d) $h _A<h _C ; K _B>K _C$
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Answer:
Correct Answer: 10. (d)
Solution:
- On smooth part $B C$, due to zero torque, angular velocity and hence the rotational kinetic energy remains constant. While moving from $B$ to $C$ translational kinetic energy converts into gravitational potential energy. So, $h _A<h _c$ and $k _B>k _C$.
