A car traveling at a speed of 18 m/s (approximately 40 MPH)

crashes into a solid concrete wall. The driver has a mass of

90 kg.

a. What is the change in momentum of the driver as he

comes to a stop?

b. What impulse is required in order to produce this change

in momentum?

c. How does the application and magnitude of this force

differ in two cases: the first, in which the driver is wearing

a seat belt, and the second, in which he is not wearing

a seat belt and is stopped instead by contact with the

windshield and steering column? Will the time of action

of the stopping force change?