Question

In the following example, try to identify the number of times the velocity of the ball changes: "A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team". Also identify the agent supplying the force in each case.

Answer 1

Below are the number of times at which the velocity of the ball changes. Whenever a force is applied on the ball then the velocity of the ball will change.
a) When the first player kicks the ball towards another player of his team then the velocity of the ball will change because the first player applies some force on the ball.
b) When another player kicks the ball toward the goal, the velocity of the ball will change, here again, the force is applied on the ball.
c) When the goalkeeper of the opposite team collects the ball, the ball's velocity will change, it becomes zero. Here the goalkeeper applies some force on the ball to stop.
d) When the goalkeeper kicks the ball towards his team, the velocity of the ball changes because the goalkeeper applies some force on the ball.