Question

Two point particles $A$ and $B$ are placed in line on a frictionless horizontal plane. If particle $A$ (mass $1kg$) is moved with velocity $10m/s$ towards stationary particle $B$ (mass = $2kg$) and after collision the two move at an angle of $45$ degrees with the initial direction of motion then find coefficient of restitution.

• A. $0$
• B. $1$
• C. $\frac{1}{2}$
• D. $\frac{1}{3}$

Answer 1

The correct option is C $\frac{1}{2}$

The co-efficient of restitution $e=\frac{velocityofseparationalonglineofimpact}{velocityofapproachalonglineofimpact}$.
or $e=\frac{v_B-v_{A}cos{90}^{\circ }}{u_{A}cos{45}^{\circ }}$
= $\frac{\frac{5}{\sqrt{2}}-0}{\frac{10}{\sqrt{2}}}$ = $\frac{1}{2}$.
Hence, $e=1/2$.