A car is traveling 20 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?

Answer 1

reaction time = 0.8 seconds at 20 m/s
distance = 0.8 s * 20 m/s = 16 m.

From v0²-v² = 2aS
where v0 and v are initial and final velocities,
a, acceleration
S, distance travelled

braking distance
= (0-20²)/(2*(-7 m/s²))
= 40.8 m.

Total distance = ?

Answer 2

40.8

Answer 3

10.5

Answer 4

not helpful