Question

A car traveling 56 km/h is 24 m from a barrier when the driver slams on the brakes. The car hits the barrier 2s later

a) what is the car's constant deceleration before the impact?

b)How fast is the car traveling at impact?

I don't get the impact parts...


I'm not entirely sure either. I can see that the average velocity v_avg=s/t or 24m/2sec
Is there some formula for average velocity in your text?


I think you have to use one of these formulas:
v=v0+at
x-x0=v0t+1/2at^2
v^2-v0^2=2a(x-x0)
x-x0=(v0+v)/2 *t
x-x0=vt-1/2 at^2

But I'm not sure if these are correct...