A two-car race

You're driving your red car. A black Porsche is in the right lane, stopped at the red light. You're traveling at 40 km/hr in the left lane, and the light turns green when you're 15 meters from the stop line. You continue at a constant speed of 40 km/hr and pass the Porsche, which accelerates from rest at a constant rate of 3 m/s2, starting at the moment the light turns green.

(a) How far from the stop line do you pass the Porsche?

(b) When does the Porsche pass you?

(c) If a Boston police officer happens to get you and the Porsche on the radar gun at the instant the Porsche passes you, will either of you be pulled over for speeding? Assume the speed limit is 50 km/hr.

You Porsche
xo -15 m 0
vo 11.11 m/s 0
a 0 3 m/s2