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

Answer 1

Force = 2200 N

Explanation:

Given : Mass = 55 kg , Velocity of car = 20 m/s , time=0.5 s

To find : Force did the seat belt put on Sarah.

Force = (mass)(acceleration) = ma

Acceleration= (Final velocity - initial velocity) / time

Final velocity
`V_f = 20 m/s` , Initial velocity
`V_i= 0` (after break car is at rest), time(t) =0.5 seconds

`a=(V_f-V_i)/(t)`

`a=(20-0)/(0.5)`

`a=40 m/s^2`

Force = mass × acceleration

`F=m* a = (55 kg)(40 m/s^2)=2200 N`

Therefore, F = 2200 N

Answer 2

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 this answer will be a good help for you.