The correct answer is option 4, negative. When a force is applied in a direction opposite to the displacement of an object, the work done on the object is considered negative.
To understand why, we need to recall the formula for work done: work = force × displacement × cos(angle between force and displacement). In this case, the force and displacement are anti-parallel, which means they are in opposite directions. As a result, the angle between them is 180 degrees, and cos(180) = -1.
Therefore, when the force is applied anti-parallel to the displacement, the work done is given by the formula work = force × displacement × -1. Since the angle is 180 degrees, cos(180) = -1, and the work done has a negative value.
This negative work done indicates that energy is being taken away from the object. In the case of dragging a mass on a horizontal plane, the force is acting against the motion, causing a decrease in the object`s kinetic energy. Hence, the work done is negative.