Two identical balls of mass 1 kg each moving towards each other with velocities of 3 m/s and 5 m/s respectively. The magnitude of the velocities of respective balls after the perfectly elastic head-on collision is

(1) 3 m/s, 5 m/s

(2) 5 m/s, 3 m/s

(3) 4 m/s, 4 m/s

(4) 6 m/s, 2 m/sIf the two masses are equal

                       
1. \(v\sqrt{\dfrac{m}{k}}\)

2. \(v\sqrt{\dfrac{2m}{k}}\)

3. \(m\sqrt{\dfrac{v}{2k}}\)

4. \(v\sqrt{\dfrac{m}{2k}}\)

The gravitational field in a region is given by $\overrightarrow{\mathrm{g}} = 4\hat{\mathrm{i}} + 4\hat{\mathrm{j}}$. Work done by this field is zero, when a particle is moved along the line

(1) 3x + 4y = 2

(2) 3x + 3y = 5

(3) x + 3y = 2

(4) 3y + x = 1

A body is under uniform circular motion, its kinetic energy.

1. depends on the direction of velocity.
2. depends on acceleration.
3.  remains unchanged.
4.  all of these.

A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration ${\mathrm{a}}_{\mathrm{r}}$ is varying with time t as ${\mathrm{krt}}^2$,where k is constant. The power delivered to the particle by the force acting on it is

(1)  $2{\mathrm{\pi kmr}}^2$

(2)  ${\mathrm{kmr}}^2\mathrm{t}$

(3)  ${\mathrm{kmr}}^2{\mathrm{t}}^5$

(4)  Zero

The ratio of the kinetic energy of a particle projected from the ground at the  highest point to point of projection is 1/4. The angle of projection with horizontal is

(1)  30°

(2)  60°

(3)  45°

(4)  53°

A bob is suspended from a peg on a wall by a massless string of length L. If it is given velocity $\sqrt{2gL}$ at the lowest point, then angular amplitude with which body will oscillate is

(1)  60°

(2)  90°

(3)  75°

(4)  30°

A bob of a simple pendulum is released from position A. Velocity of the bob when it is at lowest position A is

(1)  $\sqrt{50}$ m/s

(2)  10 m/s

(3)  5 m/s

(4)  2$\sqrt{5}$ m/s

A ball is let to fall from a height of 32 m on the ground. The coefficient of restitution is $\mathrm{e} = \frac{1}{2}$. The height raised by the ball after the second rebound is

(1)  2 m

(2)  4 m

(3)  8 m

(4)  16 m