Rotation 3 Question 2

8. Two solid cylinders P and Q of same mass and same radius start rolling down a fixed inclined plane from the same height at the same time. Cylinder P has most of its mass concentrated near its surface, while Q has most of its mass concentrated near the axis. Which statement(s) is(are) correct?

(2012)

(a) Both cylinders P and Q reach the ground at the same time

(b) Cylinder P has larger linear acceleration than cylinder Q

(c) Both cylinders reach the ground with same translational kinetic energy

(d) Cylinder Q reaches the ground with larger angular speed

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Answer:

Correct Answer: 8. (d)

Solution:

  1. IP>IQ

In case of pure rolling, a=gsinθ1+I/mR2

aQ>aP as its moment of inertia is less. Therefore, Q reaches first with more linear speed and more translational kinetic energy.

Further, ω=vR or ωv

ωQ>ωP as vP>vQ



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