# Question #5a4e5

Dec 15, 2017

The acceleration of the truck is $- 6.0 \frac{m}{s} ^ 2$

#### Explanation:

The 72 m/s is the initial speed, while zero is the final speed. Therefore, the change in speed is ${v}_{f} - {v}_{i} = - 72 \frac{m}{s}$

The acceleration is the rate at which the speed changes each second.

$a = \frac{\Delta v}{\Delta t}$

Because this happens in 12 seconds, we can write

$a = \frac{- 72}{12} = - 6.0 \frac{m}{s} ^ 2$

Note the units on acceleration $\frac{m}{s} ^ 2$ is read as "meters per second each second"