A car going 15 m/s is brought to rest in a distance of 3 m as it strikes a pile of dirt. How large a force is exerted by the seatbelts on a 90 kg passenger as the car is stopped?

Question

A car going 15 m/s is brought to rest in a distance of 3 m as it strikes a pile of dirt.  How  large a force is exerted by the seatbelts on a 90 kg passenger as the car is stopped?

Damon · Answer

average speed during stop = 7.5 m/s t = 3 meters/7.5 m/s = .4 second v = 15 + a t 0 = 15 + .4 a a = -37.5 m/s^2 F = ma = 90(-37.5) = -3375 Newtons ouch !