In coming to car stop, a car leaves skid marks 92 meters long on a highway Assuming a deceleration of .....?

Question

In coming to car stop, a car leaves skid marks 92 meters long on a highway Assuming a deceleration of 7.00m/S^2, estimate the speed of the car just before breaking, AP Physics work, highly confused, Please explain and answer if possible thanks

Answer 1

use the equation:

vf^2=v0^2 +2 ad

vf=final speed (here it is zero since the car comes to rest)

v0=initial speed (this is the variable we are solving for)

a=acceleration =-7m/s/s (be careful to use the right sign)

d=distance traveled=92 m

solve:

0=v0^2+2(-7)(92)

v0=sqrt[2(7)(92)]=35.9m/s