A motorist is travelling at 10 meters a second when he sees a deer in the road 50m ahead. If the maximum negative acceleration of his vehicle is -7 meters per second per second, then what is the maximum reaction time delta t of the motorist that will allow him to avoid hitting the deer?(adsbygoogle = window.adsbygoogle || []).push({});

I am using the equation:

change in x = initial velocity * time + (1/2) * acceleration * time squared

or:

x=v0*t+(1/2)*a*t^2

I plug all of the information in (v0 = 10, x = 50, a = -7):

50=10t-3.5t^2

... and I find no real solution. Am I doing this problem correctly and if so what does this mean in terms of a numerical answer for the reaction time of the motorist? I'm a physics dumbhead so please have mercy upon me and thanks in advance :)

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# Homework Help: 1D Kinematics problem

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