General
✓✗A particle moves in a circle of radius 2 m with a constant speed of 4 m s−1. The magnitude of its average acceleration over half a revolution is
- \( \dfrac{8}{\pi} \) m s−2
- zero
- \( \dfrac{16}{\pi} \) m s−2
- 8 m s−2
General
✓✗A body of mass 3 kg at rest explodes into two pieces of 1 kg and 2 kg. If the 1 kg piece moves with 8 m s−1, the 2 kg piece moves with
- 8 m s−1 in the opposite direction
- 4 m s−1 in the opposite direction
- 4 m s−1 in the same direction
- 16 m s−1 in the opposite direction
General
✓✗A monkey of mass 40 kg climbs a rope that can bear a maximum tension of 600 N. The rope will break if the monkey (g = 10 m s−2) (NCERT)
- climbs up with an acceleration of 6 m s−2
- climbs up with an acceleration of 4 m s−2
- climbs up with a uniform speed of 5 m s−1
- climbs down with an acceleration of 4 m s−2
General
✓✗A block of mass 10 kg is placed on a rough incline of 30° (μs = 0.5). The minimum force parallel to the incline needed to push it up is (g = 10 m s−2)
- 50 N
- 43.3 N
- 93.3 N
- 6.7 N
General
✓✗Two identical trolleys at rest are pushed apart by a compressed spring between them. Just after release they move with
- equal speeds in the same direction
- equal speeds in opposite directions
- the same velocity
- different speeds in opposite directions
General
✓✗A cyclist moving at 18 km h−1 takes a turn of radius 3 m on a level road. If the coefficient of static friction is 0.1, the cyclist (g = 9.8 m s−2) (NCERT)
- will topple outward without slipping
- will slip, since v2 > μrg
- will not slip
- will slip only if he slows down
General
✓✗Two blocks of masses 2 kg and 4 kg hang vertically, connected by a string; the upper block is pulled up by a force of 90 N. The tension in the string between them is (g = 10 m s−2)
- 30 N
- 60 N
- 90 N
- 45 N
General
✓✗A picture of weight W hangs from a nail by a string whose two halves make an angle of 120° with each other. The tension in the string is
- 2W
- \( \dfrac{W}{2} \)
- \( \dfrac{W}{\sqrt{3}} \)
- W
General
✓✗A body is hung from a spring balance in a lift. The reading is 49 N when the lift is stationary. If the lift accelerates downward at 4.9 m s−2, the reading becomes (g = 9.8 m s−2)
- 73.5 N
- 49 N
- zero
- 24.5 N
General
✓✗A force F = 100 − 2 × 104 t (in newton) acts on a body until it becomes zero. The impulse delivered is
- 2.5 N s
- 0.5 N s
- 0.125 N s
- 0.25 N s
General
✓✗A satellite in force-free space sweeps up stationary interplanetary dust at a rate dM/dt = αv, where M is the mass and v the speed of the satellite and α is a constant. The acceleration of the satellite is
- \( -\alpha v^2 \)
- \( -\dfrac{\alpha v^2}{M} \)
- \( -\dfrac{2\alpha v^2}{M} \)
- \( -\dfrac{\alpha v^2}{2M} \)
General
✓✗A constant force acting on a body of mass 3 kg changes its speed from 2 m s−1 to 3.5 m s−1 in 25 s, the direction of motion being unchanged. The force is (NCERT)
- 0.18 N opposite to the direction of motion
- 0.18 N in the direction of motion
- 4.5 N in the direction of motion
- 0.06 N in the direction of motion
General
✓✗A stone of mass 0.25 kg tied to a string is whirled in a horizontal circle of radius 1.5 m with a speed of 40 rev/min. The tension in the string is (NCERT)
- 13.2 N
- 1.1 N
- 6.6 N
- 4.4 N
General
✓✗The momentum of a body is doubled. If its mass remains constant, its kinetic energy becomes
- unchanged
- two times
- half
- four times
General
✓✗A block of mass 10 kg is placed on a rough horizontal surface with coefficient of friction μ = 0.5. If a horizontal force of 100 N acts on it, the acceleration of the block is (take g = 10 m s−2)
- 15 m s−2
- 10 m s−2
- 0.5 m s−2
- 5 m s−2