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

(a) Do you pass the Porsche? If so, how far from the stop line do you pass?

(b) When and where does the Porsche pass you?

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

To solve: organize the data & draw a diagram

• Define the stop line as the origin.
• Choose the travel direction as positive.
• Use consistent units---MKS, with speeds in m/s
  
  

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