You are a traffic accident investigator. You have arrived at the scene of an accident. Two trucks of equal mass(3,000 kg each) were involved in a rear-end accident at a stop sign. here is what you know:

Question

You are a traffic accident investigator. You have arrived at the scene of an accident. Two trucks of equal mass(3,000 kg each) were involved in a rear-end accident at a stop sign. here is what you know: 
Truck 1 approched the intersection from the top of a 22-meter hill. 
Truck 2 was on a flat stretch of road directly in front of truck 1. 
At the bottom of the hill, before braking for the stop sign, Truck 1 was going 20 m/s and truck 2 was going 35 m/s. 
From the skid marks on the road you can see that truck 1 applied force on its brakes for 2 seconds, 80 meters before the stop sign. 
There were no skid marks left by truck 2. The collision occured at the stop sign, where truck 2 had stopped. 
After the collision, both trucks were moving together in the same direction at 10 m/s, before slowly rolling to a stop. 
You must now push truck 2 using 1,000 N of force, 8 meters off the side of the road so no one else gets hurt.
How much energy did Truck 1 lose in the collision?
How much energy did Truck 2 gain in the collision?

bobpursley · Answer

1. At the bottom of the hill, before braking for the stop sign, truck 2 was going 35 m/s. The collision occured at the stop sign, where truck 2 had stopped. >> Calculte initial momentums, and initial KEnergies.
2. After the collision, both trucks were moving together in the same direction at 10 m/s, before slowly rolling to a stop.>> Calculate the momentum of the truck combinations..
3.Now, you can determine the combined velocities, which is the same as individual velocityies. Calculate the KE of each truck after the collision.
4. calcuate the energies lost/gained during the collisions.