Remember: The work done by the force exerted by the man on the lawnmower is equal to the magnitude of the displacement of the lawnmower multiplied by the magnitude of the component of force along the displacement. Thus, we need to find the component of force along the displacement of the lawnmower before we can find the work done by the man's force on the lawnmower.
But first, we must identify theta. In our example, theta is defined as the angle between the force exerted by the man and the displacement of the lawnmower. If theta was equal to zero degrees, the force would be pointed in the same direction as the displacement of the lawnmower. If theta was 90 degrees, the force would be perpendicular to the displacement of the lawnmower. And, if theta was 180 degrees, the force exerted by the man would be pointed in the direction opposite of the displacement of the lawnmower. In the picture at the right, theta (the angle between force and displacement) is somewhere between zero degrees and 90 degrees.
