a car crashes into a wall at 25m/s and is brought to rest in .1seconds. Calculate the average force exerted on a 75kg test dummy by the seat belt. How many g-forces is this? (Remember g-force= Force/mg)

Answer 1

Your questions are all the same.

av force = change in momentum/change in time
or for vanishingly small time and constant mass
force = mass * acceleration

initial momentum = m v = 75 * 25
final momentum = 0
change in momentum = -75*25
change in time = .1
so

average force = -75*25/.1 = -75*250 newtons

for number of g s
75*250/9.8