**11. **A ball moving with a velocity of 5 m/sec impinges a fixed plane at an angle of 45° and its direction after impact is equally inclined to the line of impact. If the coefficient of restitution is 0.5, the velocity of the ball after impact will be

- 0.5 m/sec
- 1.5 m/sec
- 2.5 m/sec
- 3.5 m/sec

Correct answer: (C)

2.5 m/sec

**12. **A ball of mass 1 kg moving with a velocity of 2 m/sec collides a stationary ball of mass 2 kg and comes to rest after impact. The velocity of the second ball after impact will be

- Zero
- 0.5 m/sec
- 1.0 m/sec
- 2.0 m/sec

Correct answer: (C)

1.0 m/sec

**13. **A ball of mass 250 g moving on a smooth horizontal table with a velocity of 10 m/sec hits an identical stationary ball on the table. If the impact is perfectly plastic, the velocity of the ball just after impact would be

- Zero
- 5 m/sec
- 10 m/sec
- None of these

Correct answer: (A)

Zero

**14. **A ball which is thrown upwards, returns to the ground describing a parabolic path during its flight

- Vertical component of velocity remains constant
- Horizontal component of velocity remains constant
- Speed of the ball remains constant
- Kinetic energy of the ball remains constant

Correct answer: (B)

Horizontal component of velocity remains constant

**15. **A block in the shape of a parallelepiped of sides 1m × 2m × 3m lies on the surface. Which of the faces gives maximum stable block?

- 1 m × 2 m
- 2 m × 3 m
- 1 m × 3 m
- Equally stable on all faces

Correct answer: (B)

2 m × 3 m

**16. **A block of weight 50 kg is placed on a horizontal plane. When a horizontal force of 18 kg is applied, the block is just on the point of motion. The angle of friction is

- 17° 48'
- 18° 48'
- 19° 48'
- 20° 48'

Correct answer: (C)

19° 48'

**17. **A body is dropped from a height of 100 m and at the same time another body is projected vertically upward with a velocity of 10 m/sec. The two particles will

- Never meet
- Meet after 1 sec
- Meet after 5 sec
- Meet after 10 sec

Correct answer: (D)

Meet after 10 sec

**18. **A body is said to move with Simple Harmonic Motion if its acceleration, is

- Always directed away from the centre, the point of reference
- Proportional to the square of the distance from the point of reference
- Proportional to the distance from the point of reference and directed towards it
- Inversely proportion to the distance from the point of reference

Correct answer: (C)

Proportional to the distance from the point of reference and directed towards it

**19. **A body of weight 'w' placed on an inclined plane is acted upon by a force 'P' parallel to the plane which causes the body just to move up the plane. If the angle of inclination of the plane is 'θ' and angle of friction is 'φ' , 'P' is

- w sin (φ - θ)/cos φ
- w sin (θ- φ)/cos φ
- w cos (θ+φ)/cos φ
- w sinθ cosθ - φ)/sin φ

Correct answer: (B)

w sin (θ- φ)/cos φ

**20. **A body of weight 14 g appears to weight 13 g when weighed by a spring balance in a moving lift. The acceleration of the lift at that moment was

- 0.5 m/sec
^{2} - 0.7 m/sec
^{2} - 1 m/sec
^{2} - 1 cm/sec
^{2}

Correct answer: (B)

0.7 m/sec^{2}