- #1

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## Homework Statement

What should be the spring constant k of a spring designed to bring a 1260 kg car to rest from a speed of 88 km/h so that the occupants undergo a maximum acceleration of 5.0 g?

## Homework Equations

F=ma

v

^{2}=v

_{0}

^{2}+ 2a(x-x

_{0}

F=-kx

## The Attempt at a Solution

First I converted 88km/h to 24.4 m/s

Then I found the F, by using F=ma

F= (1260) * (49) <--changed acceleration from g to m/s

^{2}

So I got 61740 for F

Then I decided to find x

I used the velocity equation

0 = (24.4)

^{2}+ 2 * -49x

Solving for x gave me 6.08

Then I plugged that into the F=-kx equation

and I got k = 10155

But this is wrong! I even tried putting in -10155

What am I doing wrong? I don't understand.