posted by Josh on .
A car is traveling 28 m/s when the driver sees a child standing on the road. He takes 0.8 s to react, then steps on the brakes and slows at 7.0 m/s2. How far does the car go before it stops?
d1=Vo*t = 28m/s * 0.8s=22.4m to react.
d2 = (Vf^2 - Vo^2) / 2a,
d2 = (0 - (28)^2) / -14 = 56m,stopping
D = d1 + d2 = 22.4 + 56 = 78.4m before