Question

Sarah, who has a mass of 55 kg, is riding in a car at 20 m/s. She sees a cat crossing the street and slams on the brakes! Her seatbelt stops her from flying forward, bringing her to rest in 0.5 seconds. How much force did the seatbelt put on Sarah? Explain how you got the answer.

Answer 1

Answer: 2200 N

Let's break down the question into an equation.

F = (mass)(acceleration) = ma

m = 55 kg

Vi = 20 m/s

t = 0.5 s

Vf = 0 m/s (since she was put to rest)

a=(Vf-Vi)/t

a=(0-20)/5

a = 40 m/s^2 (decelerating)

F = ma = (55 kg)(40 m/s^2)

F = 2200 N

Hope I helped!