A particle is thrown at an acute angle with the horizontal. Select the incorrect statement.

1.	Power delivered by gravity is zero at all the point on the trajectory.
2.	Power delivered by gravity is zero only at one point.
3.	The average power of gravity is zero.
4.	During the one-half journey, the power is negative and during the other half, the power is positive.

What is the work done by friction when the body slides down the inclined surface from A to B? 

(1) 32 J

(2) 16 J

(3) 8 J

(4) Zero

Block A moves on the smooth surface and collides with the block B at rest. The maximum energy stored in the spring will be

1.  $\frac{1}{8}{\mathrm{mv}}^2$

2.  $\frac{1}{4}{\mathrm{mv}}^2$

3.  $\frac{1}{3}{\mathrm{mv}}^2$

4.  $\frac{1}{2}{\mathrm{mv}}^2$

An object of mass 2 kg falls from rest through a vertical distance 10 m and acquires a velocity of 10 m/s. The work done by the resistive force of air on the object is (g = 10 $\mathrm{m}/{\mathrm{s}}^2$)

(1)  200 J

(2)  -200 J

(3)  150 J

(4)  -100J

A body of \(10\) kg is subjected to a force as shown in the figure. The block moves along a straight line under the influence of this force. The change in kinetic energy when the body moves from \(x=0\) to \(x=4\) m will be:

1. \(15\) J
2. \(12.5\) J
3. \(17.5\) J
4. \(19.2\) J

A constant horizontal force is applied on a block kept at rest on a smooth horizontal surface. Its power \((P)\) versus time \((t)\) graph is best shown by:

1.		2.
3.		4.

A block slides down an inclined plane of inclination 30° with a constant velocity. It then projected up with an initial speed of 6 m/s, the distance moved by it on the inclined before coming to rest is

(1)  1.5 m

(2)  1.8 m

(3)  2.0 m

(4)  2.4 m

The potential energy of a particle of mass 0.5 kg moving along x axis is given by

U = 2x (x - 3). The speed of the particle is maximum at

(1)  x = 1 m

(2)  x = 1.5 m

(3)  X = 2 m

(4)  x = 3 m

A ball strikes the floor at an angle of ${45}^{\mathrm{o}}$ with vertical and rebounds of an angle of 60° with the vertical. Assuming the contact to be smooth the coefficient of restitution is

1.  1

2.  $\frac{1}{\sqrt{2}}$

3.  $\frac{1}{3}$

4.  $\frac{1}{\sqrt{3}}$

Work energy theorem is valid in

(1)  Only inertial frame of reference

(2)  The only non-inertial frame of reference

(3)  Both inertial and non-inertial frame of reference

(4)  Does not depend on any frame of reference