A moving bicycle comes to rest after sometimes if we stop pedaling it. But Newton’s first law of motion says that a moving body should continue to move forever, unless some external force acts on it. How do you explain the bicycle case?

Which of the following effect cannot be produced by unbalanced force acting on a body?

A. Change in speed of the body

B. Change in shape of the body

C. Change in direction of motion of the body

D. Change in state of rest of the body

A plastic ball and a clay ball of equal masses, travelling in the same direction with equal speeds, strike against a vertical wall. From which ball does the wall receive a greater amount of momentum?

A man throws a ball weighing 500 g vertically upwards with a speed of 10 m/s.

(i) What will be its initial momentum?

(ii) What would be its momentum at the highest point of its flight?

A car is moving on a level road. If the driver turns off the engine of the car, the car’s speed decreases gradually and ultimately it comes to a stop. A student says that two forces act on the car which brings it to a stop. What could these forces be? Which of these two forces contributes more to slow down and stop the car?