# Instantaneous Force and Impulse

## Trending Questions

**Q.**A thin uniform rod of mass m and length l is kept on a smooth horizontal surface such that it can move freely. At what distance x from the centre of the rod should a particle of mass m strike on the rod such that the point P at a distance l3 from the end of the rod is instantaneously at rest just after the elastic collision ?

- l2
- l3
- l6
- l4

**Q.**A hammer of weight 2 kg, moving with velocity 8 m/s, strikes against the head of a spike, and drives it into a block of wood. If hammer comes to rest in 0.02 sec, the impule associated with the spike will be:

- 30 Ns
- −16 Ns
- −30 Ns
- 16 Ns

**Q.**The figure shows the position-time (x-t) graph of one-dimensional motion of a particle of mass 0.4 kg. Find the magnitude of impulse imparted to the particle at t=2 s and 4 s respectively.

- 0.2 Ns and 0.4 Ns
- 0.4 Ns and 0.4 Ns
- 0.8 Ns and 0.4 Ns
- 0.8 Ns and 0.8 Ns

**Q.**A metal plate of mass 200 gm is balanced in mid–air by throwing 40 balls/sec, each of mass 2 gm, vertically upwards from below. The balls rebound with the same speed with which they strike the plate. Find the velocity with which the balls strike the plate. (Take g=10 m/s2)

- 20 m/s
- 12.5 m/s
- 10 m/s
- 5 m/s

**Q.**A hockey player applies an average force of 60 N to 250 g hockey puck for a time of 100 ms. The impulse experienced by the hockey puck is

- 8 N-s
- 6 N-s
- 12 N-s
- 10 N-s

**Q.**A metal plate of mass 200 gm is balanced in mid–air by throwing 40 balls/sec, each of mass 2 gm, vertically upwards from below. The balls rebound with the same speed with which they strike the plate. Find the velocity with which the balls strike the plate. (Take g=10 m/s2)

- 20 m/s
- 12.5 m/s
- 10 m/s
- 5 m/s

**Q.**A gun fires 10 bullets/sec each of mass 10 gm, with a muzzle velocity of 50 m/s. Find the force required to hold the gun in position.

**Q.**A particle of mass 10 kg is moving in a straight line. If its position x with time t is given by x(t)=(t3−2t−10) m, then the force acting on it at the end of 4th second is

- 24 N
- 240 N
- 300 N
- 1200 N

**Q.**A ball moving with a momentum of 5 kg m/s strikes against a wall at an angle of 45° and is reflected at the same angle. Calculate the change in momentum (in magnitude).

- 7.07 kg m/s
- 14.04 kg m/s
- 3.53 kg m/s
- 28.08 kg m/s

**Q.**A ball of mass 100 g is projected with a velocity of 50 m/s at 37∘ from horizontal. Using the concept of impulse, find the magnitude of change in velocity of ball in 2 s (Take g = 10 m/s2)

- 70 m/s
- 20 m/s
- 30 m/s
- 10 m/s

**Q.**A metal plate of mass 200 gm is balanced in mid – air by throwing 40 balls /sec, each of mass 2 gm, vertically upwards from below. The balls rebound with the same speed with which they strike the plate. Find the velocity with which the balls strike the plate. (Take g=9.8 m/s2)

- 20 m/s
- 12.25 m/s
- 10 m/s
- 5 m/s

**Q.**A 10 g bullet moving at 100 m/s strikes a log. Assume that bullet undergoes uniform deacceleration and stops in 6.0 cm, find the magnitude of average force experienced by the log.

- 600 N
- 1233.33 N
- 833.3 N
- 1266.66 N

**Q.**A ball of mass 50 g is dropped from a height of 20 m. A boy on the ground hits this ball vertically upward with a bat with an average force of 200 N so that it attains a vertical height of 45 m. The time for which the ball remains in contact with this bat is

[Take g=10 m/s2]

- 0.0325 s
- 0.0025 s
- 0.0125 s
- 0.0225 s

**Q.**

In a cricket match, Sachin hit a 1 kg ball thrown at him at 126 km/hr exactly in the opposite direction with the exact same speed. Find the impulse that his bat imparted on the ball in the short duration for which they were in contact.

35 N

70 N

35 Ns

70 Ns

**Q.**An impulsive force (F) acts on a body which changes with time (t). The F−t graph is shown below. The value of impulse in time π sec will be:

- 350 N-s
- 200 N-s
- 250 N-s
- 300 N-s

**Q.**The displacement – time graph of a body of mass 2 kg is shown. Find the impulse acting on the body in the time interval t=2 sec to t=6 sec

- 2√3 kg m/s
- (√3+1) kg m/s
- (√3−1) kg m/s
- 2(√3−1) kg m/s

**Q.**The figure shows the position-time (x-t) graph of one-dimensional motion of a particle of mass 0.4 kg. Find the magnitude of impulse imparted to the particle at t=2 s and 4 s respectively.

- 0.2 Ns and 0.4 Ns
- 0.4 Ns and 0.4 Ns
- 0.8 Ns and 0.4 Ns
- 0.8 Ns and 0.8 Ns

**Q.**A truck of mass 2000 kg travelling at 4 m/s comes to rest in 2 s when it strikes a wall. Force exerted by the wall is

- 2 kN
- 1 kN
- 4 kN
- 8 kN

**Q.**A body is moving with velocity 30 m/s. A variable force a N is applied at t=0 s on the body such that it increases it's velocity to 90 m/s at t=4 s in same direction. The variation of force with time is shown in graph.

If mass of body is 10 kg, find the value of a (shown in graph)

- 150 N
- 100 N
- 50 N
- 125 N

**Q.**A ball of mass 100 g is projected with a velocity of 50 m/s at 37∘ from horizontal. Using the concept of impulse, find the magnitude of change in velocity of ball in 2 s (Take g = 10 m/s2)

- 70 m/s
- 20 m/s
- 30 m/s
- 10 m/s

**Q.**A gun fires 10 bullets/sec each of mass 10 gm, with a muzzle velocity of 50 m/s. Find the force required to hold the gun in position.

- 5 N
- 50 N
- 500 N
- 5000 N

**Q.**Find the velocity of the body of mass 2 kg from the momentum-time graph at the end of 5 seconds.

- 10 m/s
- 15 m/s
- 20 m/s
- 30 m/s

**Q.**A 10 g bullet moving at 100 m/s strikes a log. Assume that bullet undergoes uniform deacceleration and stops in 6.0 cm, find the magnitude of average force experienced by the log.

- 600 N
- 1233.33 N
- 833.3 N
- 1266.66 N

**Q.**In the figure given the position-time graph of a particle of mass 0.1 kg is shown. The impulse at t=2 s is :

- 0.2 kg-m/s
- −0.2 kg-m/s
- 0.1 kg-m/s
- −0.4 kg-m/s

**Q.**A ball of mass m=0.2 kg is moving with velocity vi=60 m/s and a force acts on the ball for a instant and changed its velocity to vf=90 m/s in same direction. Find the impulse imparted to the ball.

- 6 N-s
- 3 N-s
- 5 N-s
- 4 N-s