Question

Two friends on rollerskates are standing 5 m apart facing each other . One of them throws a ball of 2 kg towards the other , who catches it . How will this activity affect the position of the two ? Explain your answer .

Answer 1

Newton 's third law of motion states that every action has an equal and opposite reaction.
When one friend throws the ball towards the another he is exerting a force on the ball because of which he will also receive a force which is equal to the latter.
Now, the force can be clearly felt as the friction is reduced with the help of roller skates.
So the force pushes the person backwards.
In the same way, the ball having some force will also apply the same force on the other person as a result of which the person also moves backwards.



You start by assuming that the friction coefficient of between the roller stakes and the ice is very low and think there is not friction.
Under those circumstances the conservation of momentum implies:
1.)when the roller staker throws the 2kg ball
,it will acquire a momentum equal to v*2kg and the staker will aquire equal momentum
in the opposite direction.
That means that the staker will step back and away from other staker.

2.)when the second staker receives the ball with momentum 2kg*v,he will move back also and further away.

In conclusion,the two staker will end standing more than 5m apart facing each other.