Math CentralQuandaries & Queries


Question from Snigdha, a student:

how do you calculate work when force is negative?


Work can be negative as well. It depends on your perspective.

For example, if we declare the work done by an elevator engine lifting the carriage "positive", then the work done by gravity on the engine is negative. It depends on how you choose to label things.

Remember that Force is Mass times Acceleration. If Acceleration is negative (such as when braking), then Force is negative. Since Work is Force times Distance, if Force and Distance are different signs, then Work is negative.

Stephen La Rocque.

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS