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AP EAMCET · PHYSICS · Center of Mass Momentum and Collision

A body of mass ' m ' moving along a straight line collides with a stationary body of mass ' 2 m '. After collision if the two bodies move together with the same velocity, then the fraction of kinetic energy lost in the process is

  1. A \(\frac{1}{2}\)
  2. B \(\frac{2}{3}\)
  3. C \(\frac{3}{4}\)
  4. D \(\frac{1}{3}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{2}{3}\)

Step-by-step Solution

Detailed explanation

\(m u + 2m \cdot 0 = (m + 2m) v \Rightarrow v = \frac{u}{3}\) \(KE_{lost} = \frac{1}{2} m u^2 - \frac{1}{2} (m + 2m) v^2\) \(KE_{lost} = \frac{1}{2} m u^2 - \frac{1}{2} (3m) (\frac{u}{3})^2 = \frac{1}{2} m u^2 - \frac{1}{6} m u^2\)…