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.

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!

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.