In the \"before\" part of the figure, car A (mass 990 kg) is stopped at a traffi

Question

In the "before" part of the figure, car A (mass 990 kg) is stopped at a traffic light when it is rear-ended by car B (mass 1300 kg). Both cars then slide with locked wheels until the frictional force from the slick road (with a low ?k of 0.14) stops them, at distances dA = 7.6 m and dB = 4.5 m. What are the speeds of (a) car A and (b) car B at the start of the sliding, just after the collision? (c) Assuming that linear momentum is conserved during the collision, find the speed of car B just before the collision.

Explanation / Answer

a) Ei + Wfriction = Ef

1/2 mv^2 - u m g d = 0

0.5*v^2 - 0.14*9.81*7.6=0
v=4.57 m/s

b)
0.5*v^2 - 0.14*9.81*4.5=0

v = 3.52 m/s

c) conservation of momentum

1300*v = 990*4.57 + 1300*3.52
v=7 m/s

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.