v_{f}m_{1}v_{1}m_{2}v_{2}m_{1}m_{2}v_{f}m_{1}v_{1}m_{2}v_{2}m_{1}m_{2}v_{f}(2300 lbm)(29 ft/sec) (2800 lbm)(11 ft/sec)2300lbm 2800 lbmv_{f}19.1 ft/secForce and MotionMOMENTUM PRINCIPLESRev. 0Page 9CP-03If the initial velocities of the two objects (v and v ) are known, then the final velocity (v ) can1 2 fbe calculated by rearranging Equation 3-10 into Equation 3-11.(3-11)Example:Consider that the railroad cars in Figure 1 have masses of m = 2300 lbm and1m = 2800 lbm. The first car (m ) is moving at a velocity of 29 ft/sec and the second car2 1(m ) is moving at a velocity of 11 ft/sec. The first car overtakes the second car and2couples with it. Calculate the final velocity of the two cars.Solution:The final velocity (v ) can be easily calculated using Equation 3-8.f