A \(1500-\mathrm{kg}\) van is coasting to a stoplight at \(15 \mathrm{~m} / \mathrm{s}\). A \(1000-\mathrm{kg}\) car behind the van is doing the same thing at \(25 \mathrm{~m} / \mathrm{s}\) and crashes into the rear of the van. The bumpers collide with a coefficient of restitution of 0. 70 .

(a) What are the final velocities of the two vehicles?

(b) How much kinetic energy is converted to internal energy in this collision?

(c) How much energy is converted if the bumpers lock together in a totally inelastic collision?