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I'm trying to figure out how to find the displacement when negative work is applied. I made the question myself so it could not make any sense at all, I'm just trying to understand a concept on my own.

A car (2000kg) is moving at constant velocity at 4m/s to the right. It slows down to 1m/s in a time of 3s when an external force is applied against the car to the left. What is the displacement of the negative work?

a=change in velocity/time

F=ma

W=Fd

Ek=1/2mv^2

Using the above formulas I get an acceleration of -1m/s^2 (or 1m/s^2 left). This must mean that the force that opposes the motion of the car is -2000N (or 2000N left). The initial kinetic energy of the car is 16000J and the final kinetic energy is 1000J. The change in kinetic energy is 15000J so the work against the motion is -15000J? If so then the displacement is 7.5m? Would the displacement be positive or negative?

Thanks for any help that you can provide

## Homework Statement

A car (2000kg) is moving at constant velocity at 4m/s to the right. It slows down to 1m/s in a time of 3s when an external force is applied against the car to the left. What is the displacement of the negative work?

## Homework Equations

a=change in velocity/time

F=ma

W=Fd

Ek=1/2mv^2

## The Attempt at a Solution

Using the above formulas I get an acceleration of -1m/s^2 (or 1m/s^2 left). This must mean that the force that opposes the motion of the car is -2000N (or 2000N left). The initial kinetic energy of the car is 16000J and the final kinetic energy is 1000J. The change in kinetic energy is 15000J so the work against the motion is -15000J? If so then the displacement is 7.5m? Would the displacement be positive or negative?

Thanks for any help that you can provide

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