The Kinematic Equations

Final Velocity equation Vx= Vx0+axt Displacement equation x=Vx0(t)+ ax(t)2 Timeless Equation Vx2=Vx02+2ax(x)

vx = final velocity (m/s) vx0 = initial velocity (m/s) ax= acceleration (m/s2) x = displacement (m) t=time (s)

A person driving a car suddenly applies the brakes. The car takes 4 s to come to rest while traveling 20 m at constant acceleration. Can the speed of the car immediately before the brakes were applied be determined without first determining the car's acceleration?

(A) Yes, by dividing the distance (20 m) by the time (4 s).

(B) Yes, by determining the average speed while braking and doubling it.

(C) No, because the acceleration is needed to use standard equations such as x = v₀t + 1/2 at².

(D) No, because the fundamental relationship that defines velocity contains acceleration.