Question

2. A car is travelling at 50 km/h. The driver sees a child run out into the road 5m ahead. She applies the break and the car stops in 5 seconds. The driver's thinking time is 1.5 s. A. Will the car stop in time?

B. If the driver's thinking time is increased to 2.5 s, will the car stop in time? C. What happens if the thinking time is 1.5 s but the car is travelling at 64km/h?​

Answer 1

Anwser:

A: No

B: No

C: No

Step-by-step explanation:

V = 50km/h = 14m/s

V2 = 0m/s

t = 5s

a = V2 - V/t = -2,8m/s²

The distance the car will drive when hitting the brakes:

t = 5s

a = -2,8m/s²

v = 14m/s

d = v•t + ½a•t² = 14•5 + -1,4•25 = 35m

and 35m is greater than 5m, and this is even with not counting the thinking time(1,5s), in which the car would have traveled an extra 21m. So 56m in total.