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Class 9
Science
Force and Laws of Motion
in the following example try to identify the numb...

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:

The velocity of the football changes four times .

(i) When the first player kicks the football, its speed changes from zero to a certain value.

(ii) When another player kicks the ball towards the goal post , the direction of the ball gets changed. Therefore, its velocity also changes.

(iii) When the goalkeeper collects the ball , the speed of the ball reduces to zero from a certain value . Hence , the velocity of the ball has changed.

(iv) The goalkeeper kicks the ball towards his team players. Hence, the speed of the ball increases from zero to a certain value. Hence, its velocity changes once again.

Agent supplying the force

In first case - first player
In second case - second player
In third case - goalkeeper
In fourth case - goalkeeper

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