Question

Block 1, of mass m1 = 3.90 kg , moves along a frictionless air track with speed v1 = 31.0 m/s . It collides with block 2, of mass m2 = 51.0 kg , which was initially at rest. The blocks stick together after the collision.

What is the change ΔK=Kfinal−Kinitial in the two-block system's kinetic energy due to the collision?

Answer 1

The energy would remain equal to that of the initial kinetic energy since it is a frictionless surface. However if it is an inelastic collision then energy would be lost due to sound and heat.