physics

A driver of a car traveling at 16.7 m/s applies
the brakes, causing a uniform deceleration of
2.5 m/s2.

The first question is - How long does it take the car to accelerate
to a final speed of 13.9 m/s? For this i got 1.12 and that's correct.

The second question is - How far has the car moved during the
braking period?

Could anyone write out the formula and steps to show me how to solve this?
I keep getting 20.272 but i have already been told that it's incorrect.

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  1. assuming the 1.12 seconds is correct:

    x = xo + vo t + (1/2) a t^2
    x = 0 + 16.7 (1.12) + (1/2)(-2.5)(1.12^2)
    = 18.7 - 1.6 = 17.1

    You seem to have missed the negative sign. Your acceleration is negative. You are braking.

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