question_answer 20)

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 this own team”. Also identify the agent supplying the force in each case.  

Answer:

(i) Velocity of the football changes when first player kicks the ball towards another player of his team. (ii) Velocity of the football also changes when another player kicks the football towards the goal. (iii) Velocity of the football also changes when the goalkeeper of the opposite team stops the football by collecting it. (iv) Velocity of the football changes when the goalkeeper kicks it towards a player of his team. Thus, the velocity of the ball changes four times in this case. In first and second cases, the force is supplied by the foot of players. In third case, force is supplied by  the hands of the goalkeeper. In fourth case, as the goalkeeper hits the football with his foot, so the foot of the goalkeeper supplies the force.