Meriam, Kraige & Bolton — Kinetics of Particles: Problem 3_153

3/153 A railroad car of mass \( m \) and initial speed \( v \) collides with and becomes coupled with the two identical cars. Compute the final speed \( v' \) of the group of three cars and the fractional loss \( n \) of energy if (a) the initial separation distance \( d = 0 \) (that is, the two stationary cars are initially coupled together with no slack in the coupling) and (b) the distance \( d \neq 0 \) so that the cars are uncoupled and slightly separated. Neglect rolling resistance.