A Runaway Railroad Car, with Mass 30 *10⁴ Kg, Coasts

Multiple Choice

A runaway railroad car, with mass 30 *10⁴ kg, coasts across a level track at 2.0 m/s when it collides with a spring-loaded bumper at the end of the track. If the spring constant of the bumper is 4.0 *10⁶ N/m, what is the maximum compression of the spring during the collision? (Assume the collision is elastic.)

A) 0.77 m
B) 0.55 m
C) 0.34 m
D) 1.07 m