A particle of mass m moving with speed u collides perfectly inelastically with another particle of mass 2m at rest. Find loss of kinetic energy of system in the collision.

Explanation

To solve the problem of finding the loss of kinetic energy during a perfectly inelastic collision between two particles, we can follow these steps:

### Step 1: Determine the initial kinetic energy of the system
The initial kinetic energy (KE_initial) of the system is only due to the moving particle of mass \( m \) with speed \( u \). The particle of mass \( 2m \) is at rest, so its kinetic energy is zero.

\[ KE_{\text{initial}} = \frac{1}{2} m u^2 + 0 = \frac{1}{2} m u^2 \]
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