# Using acceleration to find distance traveled

1. Oct 2, 2008

### swede5670

1. The problem statement, all variables and given/known data
A car accelerates from 18 m/s to 45 m/s in 12 s. Assume constant acceleration.
What was its acceleration? How far did it travel?

I know that the acceleration is 2.25 m/s/s but I'm not sure how to go from acceleration to distance traveled.

2. Relevant equations
I'm guessing that its this one
vf^2 = vi^2 + 2a * ChangePosition

3. The attempt at a solution

(vf^2 - vi^2)/2a = change in position

So I get 45^2 - 18^2 / 24 which equals 70.875 meters. When I submitted the problem I got the acceleration right but I screwed up the change in position.

2. Oct 2, 2008

d = 1/2 at^2

3. Oct 3, 2008

### Mentallic

You accidentally substituted the time instead of the acceleration into your rearranged equation:

$$\Delta x=\frac{v_{f}^{2}-v_{i}^{2}}{2a}$$

4. Oct 3, 2008

### Mentallic

To use this formula, the entire equation will need to be put to use. i.e.

$$s=ut+\frac{1}{2}at^{2}$$
s = displacement
u = initial velocity