a car is proceeding at a speed of 14.0m/s when it collides with a stationary car in front. during the collision the first car moves a distance of 0.300 m as it comes to a stop. the driver is wearing her seat belt, so she remains in her seat during the collision. if the drivers mass is 52kg, how much force does the belt exert on her during the collision? neglect any friction between the driver and the seat.

2 answers

Well, force is rate of change of momentum or m A if the mass is constant, so what is the change of momentum?
original momentum of driver = 52 *14
= 588 kg m/s
final momentum of driver = 0
so change = -588 kg m/s

How long did it take?
average speed during crash = 14/2 = 7 m/s
it went .3 meters
so .3 = 7 t
t = .3 m /7 m/s = .042857 seconds (wow, fast)

so F = rate of change of momentum = -588 kg m/s / .042857s = 13,720 Newtons
For this questions guys, replace the , with a decimal point.