When Maggie applies the brakes of her car it slows uniformly from 15 point 2 m per s to 0 m per s in 2 point 50 s how far ahead of a stop sign must she apply her brakes in order to stop at the sign?

Answer 1

You haven't told us what her speed will be when she sees the sign, wrestles with her

baser instincts, triumphs over her inner struggle, and decides to stop for it. We must

assume that the 15.2 m/s that you mentioned first is her normal cruising speed. (One

reason we must assume that is because it will make the problem really easy).

Since Maggie slows the car "uniformly" (constant deceleration), her average speed during

the whole procedure is 1/2 (initial speed - final speed) = (15.2/2) m/s.

So, during a stopping maneuver, she covers (average speed) x (time) = (15.2/2) x (2.5) = 19 meters.

Since that's the distance it takes her to fully execute the maneuver to completion,

that's the distance ahead of the finish-line where she needs to initiate it.

19 meters.