You're driving down the highway at 20m/s when you see a dog you don't want to crush it 35 m in front of you. Your reaction time before stepping on the brakes is 0.5s, and acceleration created by your brakes is 10 m/s^2 what was the distance travelled before coming to a stop?

Answer 1

before you hit the brakes you go:
20*.5 = 10 meters

then
Vi = 20 m/s
a = - 10 m/s^2
v = Vi + a t
v = Vi - 10 T
0 = 20 - 10 t
t = 2 seconds to stop after hitting brakes
x = Xi + Vi t + .5 a t^2
d = 10 + 20 t - 5 t^2
d = 10 + 40 - 20
d = 30 meters
we stopped 5 meters before the dog

Answer 2

I feel bad for you. school sucks