Question

Imagine x-z plane to be fixed. A particle moving along the line 4x + 3y - 12 = 0, with a speed of 10 m/s, from the positive y-axis, approaches towards the plane and collides. If the coefficient of restitution be $e=0.75,$ then the speed of the particle after collision will be:

• A. $5m/s$
• B. $8m/s$
• C. $6\sqrt{2}m/s$
• D. $5\sqrt{2}m/s$

Answer 1

The correct option is C $6\sqrt{2}m/s$

$vsin\varphi =usin\theta ,$ $vcos\varphi =eucos\theta$

$v=u\sqrt{e^{2}co{s}^2\theta +si{n}^2\theta }$

$=10\sqrt{\left(6.75{)}^2\right(\frac{4}{5}{)}^2+(\frac{3}{5}{)}^2}$

$=6\sqrt{2}$.