Question

Two balls approach each other with same speed and undergo head on elastic collision after which one of them of mass 3kg comes to rest .The mass of the Other ball is
(1) 1 kg
(2) 3 kg
(3) 6 kg
(4) 9 kg​

Answer 1

Answer:

answer is 3kg .

hope it help you

Answer 2

Answer:

The mass of the other ball is 1 kg.

Explanation:

For elastic collision, value of coefficient of restitution = 1. Thus, velocity of separation of the balls is equal to to the velocity of approach. Thus:

$(v_1 - v_2) = (u_2 - u_1 )$

Both balls are travelling in opposite directions, thus: $u_1 = u$ and $u_2 = -u$. After collision, one ball comes to rest. Thus, $v_1 = 0$.

Putting this into the above equation:

$0-v_2=-u-u\\v_2=2u$

Now, applying law of conservation of momentum before and after the collision:

$m_1u_1 + m_2u_2 = m_1v_1 + m_2v_2$

$3u+m_2(-u)=3(0)+m_22u\\3u-m_2u=2m_2u\\3u=3m_2u\\m_2 = 1 kg$

Thus, the mass of the other ball is 1 kg.