- #1

canucklehead

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## Homework Statement

A speed trap is set up with two pressure activated strips placed across a highway, 128 meters apart. A car is speeding along at 28.8 meters per second, while the speed limit is only 19.6 meters per second. At the instant the car activates the first strip, the driver begins slowing down. What minimum deceleration (magnitude only) is needed so that the driver's average speed is within the limit by the time the car crosses the second strip?

## Homework Equations

Vf = Vi + a*t

x = Vi*t + 0.5*a*t^2

Vf^2 = Vi^2 + 2a*x

Hint: Since the driver starts with a speed that is greater than the speed limit, his final speed will need to be less than the speed limit in order for the measured average speed to equal the speed limit.

I have no idea how to start this.

help!