Question

A sphere of mass 25 Kg is moving at a speed of 1.5 m/s undergoes collision with another sphere of mass 50 Kg moving at 3m/s in the same direction, find the loss of kinetic energy when the collision is inelastic with e = 0.6.

(a) 18.75 N-m

(b) 12.00 N-m

(c) 13.75 N-m

(d) 12.75 N-m

The question was asked during an interview for a job.

This intriguing question originated from Loss of Kinetic Energy During Elastic Impact topic in chapter Kinematics & Kinetics of Motion of Machine Kinematics

Answer 1

Right option is (b) 12.00 N-m

The best I can explain: Loss of kinetic energy during inelastic collision with coefficient of restitution is given by

m1m2/(2(m1+ m2) (u1^2 – u2^2)(1-e^2))

substituting the values we get

El = 12 N-m.