# Acceleration of a car?

1. Sep 29, 2010

### ScienceGirl90

1. The problem statement, all variables and given/known data
A car is moving at 50.0 m/s and brakes to a halt in 6.00 seconds.
(1)From the time it starts braking, how far does the car travel before the car comes to a halt if its acceleration is constant?
(2)What is the car's speed 1.35 s after it starts to brake if the cars acceleration is constant?

2. Relevant equations
v=a*t+vo

3. The attempt at a solution

2. Sep 29, 2010

### fss

The equation you listed will get you the acceleration, but for the distance you'll need

$$v_f^2 = v_0^2 + 2ad$$

3. Sep 29, 2010

### ScienceGirl90

Ok thank you! I was able to find the distance for question one but I am still stuck as to what is the car's speed 1.35 s after it starts to brake if the cars acceleration is constant?

4. Sep 29, 2010

### fss

Just use the first formula you gave in your original post. Pay attention to your signs and you'll be golden.

5. Sep 29, 2010

### ScienceGirl90

Got it. Thanks!