You are driving your car along a straight, level road with n speed limit 40 mph

Question

You are driving your car along a straight, level road with n speed limit 40 mph (18 m/s). You are traveling at 15 m/s when you see a light 27 m ahead of you turn yellow. Instead of breaking, you step on the accelerator the instant you see the light turn yellow. The instant you are directly under the light, 1.5 s after you stepped on the accelerator, a cop car flashes its lights at you. At this instant, you slam on the htaV.es and come to a stop 10 m after the light. The policeperson claims that you broke the speed limit. Is this correct? Explain your reasoning.

Explanation / Answer

s = ut+(1/2)at2

27 = 15*1.5+(1/2)*a*(1.5)2

a = 4 m/s2

Speed of car below the light: v = u+at

v = 15+4*1.5

v = 21 m/s

Speed limit:18m/s

21 > 18, Yes policeperson is correct that you broke the speed limit.

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