Question

Two small spheres of equal mass, and heading towards each other with equal speeds, undergo a head-on collision (no external force acts on system of two spheres). Then which of the following statement is correct?

• A. Their final velocities must be zero
• B. Each must have a final velocity equal to the other’s initial velocity
• C. Their final velocities may be zero.
• D. Their velocities must be reduced in magnitude

Answer 1

The correct option is C Their final velocities may be zero.

Formula used: $\text{e}=\frac{{\text{v}}_2-{\text{v}}_1}{{\text{u}}_1-{\text{u}}_2}$
Nothing is mentioned about coefficient of restitution. Hence the only true statement is 'their final velocities may be zero.’