A 1500 kg mass car travelling at 25 m/s hit a wall. The front of the car is 0,5 m compressed.

Question

Find:

1. Force the wall acted on car
2. Acceleration of the car
3. Acceleration the driver was being stopped, if the seat belts let him move 20 cm forward (tenseness of seat belts during the stop didn't change)

Sorry for my poor English, I will be glad if you helped to solve these problems.

Answers: 600 kN; 400 m/s2 ; 286 m/s2

Answer 1

Given the data, you may have to solve 2 before 1.

2 Use a = (v_f²-v_i²)/2d ---this will yield a negative answer as it should since the car is decelerating.

1 Then use F=ma. Once again this will yield a negative answer since the direction of the positive velocity and the force exerted by the wall are in opposite direction.

3 For the same change in velocity, now the displacement is 0.2m. Use the same equation as in 2. Once again this will be a negative answer because the driver is also decelerating.

COMMENT: Recheck your answers. Perhaps you typed the answers to a different question by mistake.