 Classical Mechanics

# Kinetic energy lost in inelastic collisions

An $\SI{8e3}{\kilo\gram}$ truck traveling at $20\text{ m/s}$ hits a parked car of mass $\SI{2e3}{\kilo\gram}$ from behind. If the collision is perfectly inelastic, what is the approximate total loss in kinetic energy?

Assume that the road is frictionless and ignore the deformation of the vehicles. A wooden block of mass $4.8\text{ kg}$ is at rest on a frictionless floor. A bullet of mass $0.2\text{ kg}$ is fired at $500\text{ m/s}$ towards the block. If the bullet becomes embedded inside the block, how much kinetic energy is lost?

A $150\text{ kg}$ bumper car travels at $12\text{ m/s}$ due east. It hits an identical bumper car traveling due north at $16\text{ m/s}.$ If the cars lock bumpers and stick together, how much kinetic energy is lost in total?

Two balls of masses $2\text{ kg}$ and $3\text{ kg},$ respectively, move in opposite directions on a frictionless floor. Their respective speeds are $2\text{ m/s}$ and $8\text{ m/s}.$ If they stick together after a collision, how much kinetic energy is lost in total?

An eagle of mass $18\text{ kg}$ is chasing a sparrow of mass $2\text{ kg}$ from straight behind with a constant speed of $13\text{ m/s}.$ The sparrow flies away at a constant speed of $7\text{ m/s}.$ A few seconds later, the sparrow is swallowed by the eagle. If air resistance is negligible, what is the total loss in kinetic energy?

×