A 1500 kg Prius and a 2400 kg Ford F150 pickup truck are approaching an unmarked

ID: 2119522 • Letter: A

Question

A 1500 kg Prius and a 2400 kg Ford F150 pickup truck

are approaching an unmarked intersection. The Prius is headed north, and the pickup is

headed east, they both fail to stop. The Prius%u2019s onboard computer shows that its speed at

the time of impact is 13.5 m/s. The truck%u2019s speed is unknown. The accident site shows a

streak on the road, where the cars slid after they meshed together. This mark 9.5 m long,

but the police at the accident site failed to observe the angle of this skid. The cars have

average-condition tires, and the coefficient of kinetic friction of rubber on this road%u2019s

surface is 0.65. You are the expert witness.

a)What is the speed of the cars right after they mesh together (but before they skid to a stop)?

b) What is the angle of the skid mark on the road (you will send your assistant out to verify this to show you are a qualified witness)?

c)What is the speed of the Ford at the moment of impact?

a)now decceleration = 0.65*g , also v^2 = u^2 + 2as , so 0 = u^2 - 2*( 0.65*g)9.5

so u = 11m/s

c)use momentum conservation, momentum before meshing =sqrt( (1500*13.5)^2 + (2400*x)^2), where x is velocity of truck.

momentum after meshing = (1500+2400)*11, as momentum before meshing = momentum after meshing

we get x = 15.75m/s

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