What is the fractional decrease in kinetic energy of a body of mass `m_1` when it makes a head on elastic collision with another body of mass `m_2` kept at rest?

In a head on elastic collision of two bodies of equal masses

In a head on elastic collision of two bodies of equal masses

In a head on elastic collision of two bodies of equal masses

A body of mass m is at rest. Another body of same mass moving with velocity V makes head on elastic collision with the first body. After collision the first body starts to move with velocity

A particle of mass m_1 makes a head on elastic collision with another stationary body of mass m_2 , If m_1 rebounds with half of its original speed then (m_1 /m_2) is

A particle of mass m_1 , makes a head on elastic collision with another stationary body of mass m_2 If m_1 , rebounds with half of its original speed then (m_1/m_2) is