Question 1
part a ) use this two equations to find the acceleration
vf= vi + a*t
x= 0.5*a*t^2 + vi*t
You have two equations in two unknowns, a and t. Find a .
part b ) use this equation first to find the acceleration
vf^2 = vi^2 + 2ax
then after finding a use this equation to find the net force in car which is basicly the weight of it. there is no friction because the car has stopped after collision so don't worry about the frictional force.