Question

You are riding a unicorn at 25 m/s and come to a uniform stop at a red light 20 m away what s your acceleration?

Answer 1

$v_f^2 -v_i^2 = 2ax \\ 0 -25^2 = 2a \times 20 \\ a = \frac{-625}{40} = -15.625 \; m/s^2$