Homework Help: Physics

Posted by Sarah on Wednesday, September 26, 2012 at 10:22am.

You are driving to the grocery store at 11.9m/s. You are 169.0m from an intersection when the traffic light turns red. Assume that your reaction time is 0.730s and that your car brakes with constant acceleration. How far are you from the intersection when you begin to apply the brakes?
a). What acceleration will bring you to rest as you just reach the intersection?
b). How long does it take you to stop?

Physics - Elena, Wednesday, September 26, 2012 at 11:35am
s= 169 - v•t₀=169-11.9•0.73=160.3 m
a=v²/2s=11.9²/2•160.3=0.44 m/s²
0=v-at
t=v/a=11.9/0.44=26.9 s.
Physics - joane, Sunday, September 30, 2012 at 8:05pm
I dont think b) is correct because im getting an incorrect answer

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