Q.

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]

1 Both cylinders P and Q reach the ground at the same time.  
2 Cylinder P has larger linear acceleration than cylinder Q.  
3 Both cylinders reach the ground with same translational kinetic energy.  
4 Cylinder Q reaches the ground with larger angular speed.  

Ans.

(4)

As we know, acceleration of the center of mass of a cylinder rolling down an inclined plane

               ac=gsinθ1+IMR2

In case of P the mass is concentrated away from the axis,

So IP>IQ

 aP<aQ  vP<vQ  ωP<ωQ