Question

Two identical balls A and B lie on a smooth horizontal surface, which gradually merges into a curve to a height $3.2$m. Ball A is given a velocity $10$m/sec to collide head on with ball B, which then takes up the curved path. The minimum coefficient of restitution 'e' for the collision between A and B, in order that B reaches the highest point C of curve. $(g=10m/se{c}^2)$.

• A. $\frac{1}{2}$
• B. $\frac{3}{5}$
• C. $\frac{1}{4}$
• D. $\frac{3}{4}$

Answer 1

The correct option is D $\frac{3}{4}$

To reach height point h = 3.2m

the minimum velocity of B at bottom required is $V_b$ say.

$0-V_b^2=-2gh$

$V_b=\sqrt{2gh}=8m/s$

$e=\frac{V_b}{V_a}=\frac{8}{10}=0.8$ minimum