# A driver of a car traveling at 15.0 m/s applies the brakes, causing a uniform acceleration of -2.0 m/s^2. How long does it take the car to accelerate to a final speed of 10.0 m/s? How far has the car moved during the braking period?

##### 1 Answer

Time needed: **2.5 s**

Distance covered: **31.3 m**

#### Explanation:

I'll start with the distance covered while *decelerating*. Since you know that the initial speed of the car is **15.0 m/s**, and that its final speed must by **10.0 m/s**, you can use the known acceleration to determine the distance covered by

Isolate

To get the time needed to reach this speed, i.e. **10.0 m/s**, you can use the following equation

**SIDE NOTE** *I left the value I got for the distance rounded to three sig figs*.