Question

Two masses, each weighing 1.0 × 103 kilograms and moving with the same speed of 12.5 meters/second, are approaching each other. They have a head-on collision and bounce off away from each other. Assuming this is a perfectly elastic collision, what will be the approximate kinetic energy of the system after the collision?

A. 1.6 × 105 joules
B. 2.5 × 105 joules
C. 1.2 × 103 joules
D. 2.5 × 103 joules ...?

Answer 1

A. 1.6 × 105 joules

Answer 2

A perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. Therefore, we just add the kinetic energies of each system. We calculate as follows:

KE = 0.5(1.0 × 10^3)(12.5 )^2 + 0.5(1.0 × 10^3)(12.5 )^2
KE = 156250 J = 1.6 x 10^5 J -------> OPTION A