Question

A ball moving with a speed of 2.2 m/sec strikes an identical stationary ball. After collision the first ball moves at 1.1 m/sec at ${60}^0$ with the original line of motion. The magnitude and direction of the ball after collision is

• A. $5m/sec,{90}^0$
• B. $2m/sec,{60}^0$
• C. $\sqrt{39\left(1.1\right)}m/sec,{30}^0$
• D. $10m/sec,{60}^0$

Answer 1

Answer: (C)

$\sqrt{39\left(1.1\right)}m/sec,{30}^0$

Conserving momentum in X - direction

$m\times 2.2=1.1\times m\times cos60+vcos\theta \times m$

$2.2=\frac{1.1}{2}+vcos\theta$

$\frac{3.3}{2}=vcos\theta$........................(1)

Similarly in Y - direction

$vsin\theta =1.1sin60$

$vsin\theta =\frac{1.1\sqrt{3}}{2}$........................(2)

from (1) & (2)

$v=\sqrt{3.9\left(1.1\right)}m/s$

$\theta ={30}^0$