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.
Velocity has both magnitude and direction. Thus change in any of magnitude or direction results in change in velocity.
In the given case, when player kicks the ball to another player the direction of ball is changed thus velocity is changed.
The second player then pushes the ball in forward direction, so velocity changes. Then the goalkeeper brings ball at rest hence velocity changes (magnitude is changed). After that he kicks the ball thus increase the speed and direction is opposite, hence velocity changes again.
The agent of supplying force are 1st player, 2nd player, goalkeeper and goalkeeper respectively.