What are unbalanced forces? Give examples.

What is relationship between mass and inertia? Give the SI unit of mass and inertia.

By how much does the momentum of a body of mass 5kg change when its speed.

(i) decrease from 20 m/s to 0.20 m/s; and

(ii) increases from 30 m/s to 40 m/s?

State the law of conservation of momentum. Write the equation describing the principle.

From a rifle of mass 4 kg, a bullet of mass 5 g is fired with an initial velocity of 35 \(m s^{-1}\) Calculate the initial recoil velocity of the rifle.

A bullet of mass 20 g moving with a speed of \(500 m {s}^{-1}\) strikes a wooden block of mass 1 kg and gets embedded in it. Find the speed with which block moves along with the bullet.

A body of mass 2 kg, initially moving with a velocity of \(10 m {s}^{-1}\)collides with another body of mass 5 kg at rest. After collision velocity of ifrst bdy becomes \(1 m {s}^{-1}\) .Find the velocity of the second body.

A boy of mass 60 kg running at 3 m/s jumps on to a of mass 140 kg moving with a velocity of 1.5 m/s in the same direction. what is their common velocity?

A 8000 kg engine pulls a train of 5 wagons, each of 2000 kg, along a horizontal track. If the engine exerts a force of 40000 N and the track offers a friction force of 5000 N, then calculate:
(a) the net accelerating force;
(b) the acceleration of the train;

Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions, The velocity of each object is \(2.5 m s^{-1}\) before the collision during which they stick together. What will be the velocity of the combined object after collision?

An object of mass 1 kg travelling in a straight line with a velocity of 10 m s^–1 collides with, and sticks to, a stationary wooden block of mass 5 kg. Then they both move off together in the same straight line. Calculate the total momentum just before the impact and just after the impact. Also, calculate the velocity of the combined object.

The following is the distance-time table of an object in motion:

(a) What conclusion can you draw about the acceleration? Is it constant, increasing, decreasing, or zero?
(b) what do you infer about the forces acting on the object?

A motorcar of mass 1,200 kg is moving along a straight line with velocity of 90 km/h. Its velocity is slowed down to 18 km.h s by an unbalanced external force. Calculate the acceleration and change in momentum. Also, calculate the magnitude of the force required.

A large truck and a car, both moving with a velocity of magnitude v, have a head on collision and both of them come to a halt after that. If the collision late for 1 s:
(a) which vehicle experiences the greater force of impact?
(b) Which vehicle experiences the greater change in momentum?
(c) Which vehicle experiences the greater acceleration?
(d) Why is the car likely to suffer more damage than the truck?

The second law of motion is often seen in action in our everyday life. You must have noticed that while catching a fast moving cricket ball, a fielder in the ground gradually pulls his hands backwards with the moving ball. In doing so, the fielder increases the time during which the high velocity of the moving ball decreases to zero. Thus, the acceleration of the ball is also reduced. If the ball is stopped suddenly then its high velocity decreases to zero in a very short interval of time. Thus the rate of change of momentum of the ball will be large. Therefore, a large force would have to be applied for holding the catch that may hurt the palm of the fielder.
(a) State Newton second law of motion.
(b) State relation between force of momentum.
(c) What is the SI unit of force?
(d) Why we are hurt less when we jump on a muddy floor in comparison to a hard floor?