I'm a hurry to go to work today because I forgot to set my alarm clock and woke up late. I'm driving my car very fast, with a velocity of v=40 m/s and coming up to an intersection with a stoplight. When the distance between my car and the intersection is L=100 m, the light turns yellow and I immediately hit the brakes and start to slow down with a constant acceleration. Find the magnitude of my acceleration in m/s2 if my car stops right at the intersection.

Answer 1

V^2 = Vo^2 + 2a*d.
a = (V^2-Vo^2)/2d
a = (0-(40)^2)/200 = -8 m/s^2.