Physics B
posted by Bob on .
A car slows down from 23 m/s to rest in a distance of 85m. What is its constant acceleration?
I got 6.224, but a friend was telling me it's 3.11 and that I had to divide by 2. Why is that?

The average velocity during deceleration is 11.5 m/s. The time required to decelerate is 85/11.5 = 7.39 s
The acceleration rate is 23 m/s/7.39s = 3.11 m/s^2
I added the minus sign because it is decelerating 
How did you get the average velocity?

i think 3.11

A car slows down uniformly from a speed of 15.0 m/s to rest in 6.00 s .