# NEET Physics Systems of Particles and Rotational Motion Questions Solved

A block of mass m moving at a velocity v collides with another block of mass 2m at rest. The lighter block comes to rest after collision. Find the coefficient of restitution.

(a) $\frac{1}{2}$                                               (b) $1$

(c) $\frac{1}{3}$                                               (d) $\frac{1}{4}$

From conservation of linear momentum we can see that velocity of 2m will become $\frac{\mathrm{v}}{2}$ after collision (as mass is doubled)

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PMT - 2011

A small mass attached to a string rotates on a frictionless table top as shown. If the tension on the string is increased by pulling the string causing the radius of the circular motion to decrease by a factor of 2, the kinetic energy of the mass will

(a) Increase by a factor of 4                                       (b) Decrease by a factor of 2

(c) Remain constant                                                   (d) Increase by a factor of 2

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PMT - 1997

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A particle of mass 1 kg is kept at (1m, 1m, 1m). The moment of inertia of this particle about z-axis would be

1.

2.

3.

4.  None of these

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