Question

A 15.0 m long truck traveling at 40.0 mph has a braking capability of 5.00 m/s2 from this speed. It is approaching a 10.0-m wide intersection with a traffic light that is turning yellow. (a) What is the minimum distance the truck can be from the intersection if the truck is to stop before it enters the intersection? (b) Assuming the truck continues at constant speed from this minimum distance, for how long must the light remain yellow for the truck to completely clear the intersection before the light turns red?

Answer 1

V=40mi/h * 1600m/mi * 1h/3600s.=17.8m/s

V^2 = V0^2 + 2a*d.
d=(V2-Vo^2)/2a=(0-(17,8)^2)/-10=31.7 m =
Stopping distance.

b. d = V*t = 10+15
17.8*t = 25
t = 1,40 s.