Rate of Deceleration & Time Required

[dgsigala]

Homework Statement

A truck traveling at 40.0 m/s decelerates uniformly to 20.0 m/s over a distance of 100 m. Determine the rate of deceleration and the time required for the truck to travel the 100 m.

Homework Equations

Deceleration=(original velocity-final velocity)/Time

The Attempt at a Solution

 

[Basic_Physics]

Rather try and use
s=ut + $\frac{1}{2}$at²
or
v²=$\!$$\:$u²+2as