While traveling north on an expressway, a car traveling 60 mph (miles per hour) slows down to 30 mph in 12 minutes due to traffic conditions. calculate the acceleration. a = mi/h2

- 30 miles / h^2

Explanation:

This problem requieres that you assume uniformly accelarated motion.

1) Data:

Vo = 60 miles / h
Vf = 30 miles / h
t = 12 min
a = ?

2)  Formula:

Vf = Vo + at

3) Clear t:

a = [Vf - Vo] / t

4) convert t = 12 min to hours

t = 12 min * 1 h / 60 min = 0.2 h

5) Substitute the data into the formula

a = [30 miles/h - 60 miles/h]/0.2 h = - 30 miles / h^2

The negative sign means that the car decelerated.
- 30 miles / h^2