Question

A ball collides with a smooth fixed wall with a velocity $10m/s$ and returns with a velocity $6m/s$. Considering oblique collision, the coefficient of restitution $e$ can not be:

• A. $0.8$
• B. $0.6$
• C. $0.5$
• D. $0.4$

Answer 1

The correct option is A $0.8$

In figure a $v=\sqrt{{100}^2-u^2}$

after collision.

$v^{\prime }=ev\sqrt{6^2-u^2}=e\sqrt{{100}^2-u^2}e=\frac{\sqrt{6^2-u^2}}{\sqrt{{100}^2-u^2}}$

where $0\le u^2\le (6{)}^2$

Hence $0\le e\le 0.6$