A ball of mass m is moving normally towards a wall of mass $$M($$ $$m)$$ with a velocity $$4$$ $$m/s$$. The wall is also moving. After striking elastically with the wall, velocity of ball becomes $$8$$ $$m/s$$. Find the speed of the wall :

Question

A ball of mass m is moving normally towards a wall of mass $$M($$>> $$m)$$ with a velocity $$4$$ $$m/s$$. The wall is also moving. After striking elastically with the wall, velocity of ball becomes $$8$$ $$m/s$$. Find the speed of the wall :

Infinity Learn · Accepted Answer

Let V be the velocity of ball. Relative velocity of separation $$=$$ relative velocity of approach. $$v2-v1=u1-u2$$ ; $$v2+u2=u1+v1$$    as the velocity of the heavier body does  not change after $$collision2u2=4-8=-4$$  and $$u2$$ $$=-2m/svelocity$$ of the $$wall=$$ $$-2$$ $$m/s$$ i.e. towards  the ball

A ball of mass m is moving normally towards a wall of mass M(>> m) with a velocity 4 m/s. The wall is also moving. After striking elastically with the wall, velocity of ball becomes 8 m/s. Find the speed of the wall :

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