# physics

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what distance should you keep between you and the car in front of you if the traffic is moving at 65mph? Your reaction time is 1s, and both the cars can decelerate at the same rate. Include reasonable estimate for the length of the car (you don't want your bumper to end up at the same location as the bumper or even the rear of the car in front of you).

65mph=29.05m/s
t=1s
a=constant
d=?

I am having trouble solving this problem. Would I use:
delta d = v_f^2 - v_0^2/(2a) But i don't think this is correct because there's no t and I also don't have a definite number for a. OR is the correct equation: d=d_0+v_0t+1/2at^2
but again I don't know a. Thanks in advance for your help. I really appreciate it.

• physics -

Why don't you find the final position when both have stopped, assuming the front car was d ahead at time zero? If the front car ends up behind the back car, a collision occured. You will need to adjust d to not let that happen.

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