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A 3000 lb car is loaded on a 30000 lb barge, initially at rest. Car suddenly departs the barge with a velocity of 5mph relative to the barge. Determine velocity of barge caused by cars motion.

Attempt at solution

V(c/b) 5mpn = 7.33 f/s

Vc = Vb +V(c/b)                                             Mc(Vc)1 + Mb(Vb)1 = Mc(Vc)2 + Mb(Vb)2
                         
Vc = Vb + 7.33                                                  0 + 0 = 3000(Vc)2 + 30000(Vb)2

                                                                          (Vc)2 = -10(Vb)2


-10(Vb)2 = (Vb)2 +7.33                                       (Vc)2 = -10(-0.666)

-11(Vb)2 = 7.33 f/s                                             (Vc)2 = 6.66 f/s

(Vb)2 = 0.666 f/s