Question

5. How long does it take a car to cross a 30 m wide intersection after the light turns green after waiting at a traffic light, assuming the car accelerates at a constant 2.0 m.s2. Ignore the driver’s reaction time

Answer 1

S = Vo t + 1/2 a t^2 = 1/2 a t^2 V0 = 0 for a standing start

t = (2 S / a)^1.2

t = (2 * 30 / (2.0) = (30)^1/2 = 5.5 sec