Question

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?

• A. Cylinder Q reaches the ground with larger angular speed
• B. Cylinder P has larger linear acceleration than cylinder Q
• C. Both cylinders reach the ground with same translational kinetic energy
• D. Both cylinders P and Q reach the ground at the same time

Answer 1

The correct option is A Cylinder Q reaches the ground with larger angular speed

$a_{cm}=\frac{g\sin \theta }{1+\frac{I_{cm}}{m{R}^2}}$
$I_{cmP}>I_{cmQ}$
$\Rightarrow a_{cmQ}>a_{cmP}$
Thus Q reaches the ground with larger angular speed.