Car stopping on a dime

1. Feb 2, 2012

Loren Booda

What is the g-force on a car, initially traveling at 55 mph, when stopping across the diameter of a dime?

2. Feb 3, 2012

Pythagorean

convert mph to mps, find the acceleration from change in velocity, multiply by mass, divide by g.

3. Feb 3, 2012

Pythagorean

Find acceleration from change in velocity over given distance, that is.

4. Feb 3, 2012

KingNothing

Would it not be appropriate to solve a system of equations, d=1/2 * a * t^2, d = 17.91 mm, and a * t = 55 mph?

Doing this I get about 16.9 kilometers / s^2, or 1721g.

Last edited: Feb 3, 2012
5. Feb 3, 2012

Pythagorean

$$a = \frac{v^2 - v_0^2}{2d}$$

but $$v_0 = 0$$ (in my ref frame : )

so

$$a = \frac{v^2}{2d}$$

Of course, this assume constant acceleration...