Two cars collide at an intersection. Car A, with a mass of 2000 kg , is going fr

Question

Two cars collide at an intersection. Car A, with a mass of 2000 kg , is going from west to east, while car B , of mass 1400 kg , is going from north to south at 17.0 m/s . As a result of this collision, the two cars become enmeshed and move as one afterward. In your role as an expert witness, you inspect the scene and determine that, after the collision, the enmeshed cars moved at an angle of 65.0 south of east from the point of impact.

1. How fast were the enmeshed cars moving just after the collision?

2. How fast was car A going just before the collision?

Explanation / Answer

add the momentum vectors. A has a momentum Pa = 1900*Va angle 0 B has a momentum Pb = 1400*17 angle -90 = 23800 angle -90 R has momentum R = R angle -65 Ax = 1900*Va Bx = 0 Rx = Rcos(-65) Ay = 0 By = -23800 Ry = Rsin(-65) summing x and y 1900*Va = Rcos(-65) -23800 = Rsin(-65) from the last, R = 26260 1900*Va = Rcos(-65) 1900*Va = 26260 cos(-65) Va = 5.84 m/s (b) total mass is 3300 kg, so if total momentum (R) is 26260, them Vr = 26260/3300 = 7.96 m/s (a)

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