posted by Emily .
A driver entering the outskirts of a city takes her foot off the accelerator so that her car slows down from 90 km/h to 50 km/h in 10 s. Find the car's average acceleration.
Change the speeds to m/s, then divide the difference by 10 s.
The change in speed is -40 km/h, which is -11.11 m/s
The acceleration rate will be negative