# Deceleration Question

1. Sep 9, 2007

### Champ07

1. The problem statement, all variables and given/known data
A 27 lb meteorite struck a car, leaving a 27 cm deep in the trunk. If the meteorite stuck the car with a 520 m/s what was the magnitude of deceleration assuming it to be constant

2. Relevant equations
None

3. The attempt at a solution
I have to be honest I have no clue whatsoever could someone please direct me on how to just attack this question because I have no idea where to begin

2. Sep 9, 2007

### bel

Use the simultaneous equations $$s=vt-\frac{1}{2}at^2$$ and $$s=ut+\frac{1}{2}at^2$$.

3. Sep 9, 2007

### Champ07

Sorry if this is a stupid response but I just started taking Physics this week and have no idea what those letters stand for.

4. Sep 9, 2007

### bel

Well, "s" is the distance, which would be the distance of penetration in this case, "a" is the acceleration, "t" is the time, "v" is the final velocity, and "u" is the initial velocity.

5. Sep 9, 2007

### Champ07

So s = 27 cm, a = what your looking for v = 0 m/s u = 520 m/s whats the time here?

6. Sep 9, 2007

### rocomath

if you're not given time, you will need to choose a diff eqn or you can plug 1 eqn into another to get rid of time.

7. Sep 9, 2007

### hage567

If you look at your kinematic equations, can you find one that relates all the things you have there without time? You don't need time to solve this problem. You can do it with one equation.