We know that work can be either positive or negative; now let's find out why with an example. The work in our example will be done by the external force exerted on a lawnmower by a man. If you look at the image at the right, you can see that the man exerts an external force on the lawnmower, and the force points downward and to the right while the displacement of the lawnmower points to the right. In other words, the man is pushing downward and to the right on the lawnmower, but the lawnmower moves to the right. |