How do I determine how far a car I am driving at 100 km/h would travel between the time ( 0.18s) you see an emergency and the time you slam on the brakes. Express the answer in metres.

Question

anonymous · Answer

I learned that I have to do use this formula:

Vf - Vi = at
Xf - Xi = Vavg t
Vavg = Vi + Vf
           -------
                2

kainui · Answer

Initial velocity is the same as your final velocity, 100km/h. The change in time is .18s. There is no acceleration between when you see the emergency and when you respond to it. Your Xinitial is 0 when you see it and your Xfinal is when your foot hits the break after .18s. So what formula uses this knowledge to solve for Xfinal?

Xf=Xi+Vavg*t

But don't forget you need to get it in m/s from km/h like this:

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