0.6 -0.41 s 0.5 VO 0.4 0.5 in. 0.3 0.2 0.12 in. 0.1 -0.1 0.2 0. 0.6 0.8 Time (s) -0.2 -0.3 (1) (2) Displacement (in.)

A loaded railroad car weighing 30,000 lb is rolling at a constant velocity v0  when it couples with a spring and dashpot bumper system (Fig. 1). The recorded displacement–time curve of the loaded railroad car after coupling is as shown (Fig. 2). Determine (a) the damping constant, (b) the spring constant. (Hint: Use the definition of logarithmic decrement given in 19.129.)