Question

A perfectly hard billiard ball of kinetic energy $E_k$ collides with another similar ball at rest. After the collision the kinetic energy of the first ball becomes ${E_k}^{\prime }$. Then-

• A. ${E_K}^{\prime }=E_K$
• B. ${E_K}^{\prime }>E_K$
• C. ${E_K}^{\prime }<E_K$
• D. ${E_K}^{\prime }=E_K^2$

Answer 1

The correct option is C ${E_K}^{\prime }<E_K$

When two similar balls collide, they exchange energies depending on the collision.

If head on, then complete exchange, if obligue then partially.

Here, second ball is at rest. Thus, There is transfer of energy from first to second.

Thus first ball loses energy.