In a chain reaction car accident on the North-South tollway, a BMW with a mass o
ID: 1700502 • Letter: I
Question
In a chain reaction car accident on the North-South tollway, a BMW with a mass of 2000 kg collides elastically with a Honda Civic (mass 1500 kg) at rest. The Honda in turn collides with a Hummer of mass 3000 kg in front of it, that’s also at rest, and the Honda and the Hummer lock bumpers and slide forward with a velocity of 3 m/s. (The BMW that originated the chain of events is not involved in the second collision). What was the velocity of the Honda right after the first collision and before it hits the Hummer?What was the velocity of the BMW right before the first collision?
Explanation / Answer
1. conservation of momentum. 3*(3000+1500)=v*1500. so v=9(m/s). 2. assume that velocity of the BMW is v. we have v1=v, v1'=v'. v2=0. v2'=9. v2'=(v2*(m2-m1)+2m1*v1)/(m1+m2). so that v2'=2m1v1/(m1+m2). so v1=7.9(m/s) 3.we have v1'=(v1*(m1-m2)+2m2v2)(m1+m2)=1.125(m/s)