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## Homework Statement

A pullback toy car is pulled back. How far will it go before it stops?

x(0)=0

v(0)=0

a(x<x

_{0})=-k(x

_{0}-x)

a(x>

_{x0})=μg

v(t

_{f})=0

t

_{f}=D

## Homework Equations

F

_{s}=-kx

F=mg

F

_{f}=μF

## The Attempt at a Solution

d

^{2}x/dt

^{2}=1/m(k(x

_{0}-x)-μmg)

Later in the run spring constant is irrelevant, so

d

^{2}/dt

^{2}=1/m(-μmg)

I think I can figure out the μ by pulling the car back on the ramp and lowering the angle between the ramp and the surface until car starts rolling. Then the tangent of that angle tanθ=μ

Would this be correct? Also, what experiment or method would you propose to figure out the coefficient of spring? Disassembling the toy is not an option.

I apologize I didn't put formulas the proper way, however I couldn't get Latex to work even though I followed FAQ instructions.

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