Question

A car is traveling at a constant velocity of 21 m/s (about 45 mph). The driver sees a fallen tree lying across the road and hits the brakes after a delay (reaction time) of 245 ms. (1 ms = 10-3 s.)
Calculate the distance the car travels during this 245 ms reaction time period.

Once the brakes are applied, the car slows to a stop with an acceleration of -5.29 m/s2. Calculate the distance the car travels while the brakes are applied.

Answer 1

d = Vo*t = 21m/s * 0.245s =

V^2 = Vo^2 + 2a*d.
V = 0.
Vo = 21 m/s.
a = -5.29 m/s.
d = ?.

Answer 2

89