Question

The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with acceleration of -5.55 m/s2 for 4.40 s, making straight skid marks 63.9 m long, all the way to the tree. With what speed does the car then strike the tree?

Answer 1

First of all you should find initial speed by using

x=Vin*t + (a*t^2)/2

then you can calculate final speed by using

Vfin=Vin + a*t