Question

A moving body makes a perfectly inelastic collision with a second body of equal mass at rest K.E lost during collision is ___________ of initial K.E.

• A. 1/4
• B. 1/2
• C. 1
• D. 0

Answer 1

The correct option is B 1/2

Using linear momentum conservation

$m\times u+m\times 0=2m\times v$

$\Rightarrow v=\frac{u}{2}$

fraction of K.E lost=$\frac{\frac{1}{2}m{u}^2-\frac{1}{2}\times 2m\times v^2}{\frac{1}{2}m{u}^2}$

Hence fraction of kinetic energy lost = $\frac{1}{2}$