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## Homework Statement

With brakes fully applied, a 1670 kg car decelerates from a speed of 78.0 km/hr. What is the work done by the braking force in bringing the car to a stop?

What is the change in the kinetic energy of the car?

## Homework Equations

W=f*s, KE= .5(m)(v^2)

## The Attempt at a Solution

I am not sure if for the first answer how to start the problem, I have the mass, but I do not know the acceleration to solve for F...how can I go about solving this problem? Also for the second question I thought I would just have to use the equation for KE to solve, but it doesn't seem to be working...any suggestions?