A stone of mass m is thrown from the earth's surface at an angle $\mathrm{\alpha }$ to the horizontal with an initial velocity ${\mathrm{v}}_0$. Ignoring the air drag, the power developed by gravitational force t second after the beginning of motion is:

(1)  $\mathrm{mg}\left(\mathrm{gt} - {\mathrm{v}}_0\mathrm{sin\alpha }\right)$

(2)  ${\mathrm{mgv}}_0\mathrm{sin\alpha }·\mathrm{t}$

(3)  $\mathrm{mg}\left(\mathrm{g} - \mathrm{vsin\alpha }·\mathrm{t}\right)$

(4)  Zero

An ideal horizontal spring has been compressed by two masses of 1 kg and 4 kg at its ends placed on a frictionless table. The stored energy is 40 joule. If the spring is released, the lighter mass will acquire a speed of:

(1)  2 m/s

(2)  4 m/s

(3)  8 m/s

(4)  16 m/s

A car of mass 100 kg and traveling at 20 m/s collides with a truck weighing 1 tonne traveling at 9 km/h in the same direction. The car bounces back at a speed of 5 m/s. The speed of the truck after the impact will be:

1.  11.5 m/s

2.  5 m/s

3.  18 m/s

4.  12 m/s

If work done by the string on block A is W, shown in the given arrangement, then the work done by the string on block B is

1.  -W

2.  $-\frac{2\mathrm{W}}{3}$

3.  $\frac{3\mathrm{W}}{2}$

4.  $\frac{2\mathrm{W}}{3}$

Which of the following remains unchanged (for the system) during an inelastic collision?

The position (in meter) of a particle of mass 1 kg confined to move along the y-axis varies with time (in second) as y= ${\mathrm{t}}^2$ - 4t+ 5. The work done by all the forces acting on the particle during t = 0 to t = 4 s is

(1)  8 J

(2)  16 J

(3)  32 J

(4)  Zero

A particle is dropped from a height of 50 m. If the particle loses its 20% mechanical energy during the impact with the ground, up to what height will it rebound after the second impact?

(1)  40 m

(2)  36 m

(3)  32 m

(4)  28 m

A body of mass 2 kg is rotating in a vertical circle of radius 4 m. The difference in its kinetic energy at the top and bottom of the circle is:

(1)  40 J

(2)  80 J

(3)  120

(4)  160 J

If a stone is projected vertically upward from the ground with a speed of 10 m/s, then it's: (g = 10 $\mathrm{m}/{\mathrm{s}}^2$)

1.  Potential energy will be maximum after 0.5 s

2.  Kinetic energy will be maximum again after 1 s

3.  Kinetic energy = potential energy at a height of 2.5 m from the ground

4.  Potential energy will be minimum after 1 s

A body of mass m strikes with the ground with speed u and coefficient of restitution is e, then find the work done by normal reaction force on the body.

1.  zero

2.  $\frac{1}{2}{\mathrm{mu}}^2\left({\mathrm{e}}^2 - 1\right)$

3.  $\frac{1}{2}{\mathrm{mu}}^2\left(1 - {\mathrm{e}}^2\right)$

4.  $\frac{1}{2}{\mathrm{mu}}^2$