Question

Two balls A and B having masses 1 kg and 2 kg, moving with speeds 21 m/s and 4 m/s respectively in opposite directions, collide head on. After collision A moves with a speed of 1 m/s in the same direction, then the coefficient of restitution is

• A. 0.1
• B. 0.2
• C. 0.4
• D. None

Answer 1

The correct option is B

0.2

Applying conservation of momentum
1(21)-2(4) = 1(1)+2v
⇒ 2v = 12
$V=6m{s}^{-1}$
We have, E = $\frac{v_2-v_1}{u_1-u_2}$
$=\frac{6-1}{21-(-4)}=\frac{5}{25}=0.2$