Question

Two spheres are moving towards each other. Both have same radius but their masses are 2 kg and 4 kg. If their velocities are 4 m/s and 2 m/s respectively and coefficient of restitution is e = 1/3, find the common velocity along the line of impact.

• A. 0 m/s
• B. 8 cos ${30}^{\circ }$ m/s
• C. 4 cos ${30}^{\circ }$ m/s
• D. 6 cos ${30}^{\circ }$ m/s

Answer 1

The correct option is A 0 m/s

Answer is A.
By conservation of momentum along line of impact
$2\left(4cos{30}^{\circ }\right)-4\left(2cos{30}^{\circ }\right)=(2+4)v$
Therefore, V = 0 (common velocity along LOI). Please refer the given image.