Question

Can work done be positive, negative and zero? Explain.

Accepted Answer

The product of the component of the force in the displacement direction and the magnitude of the displacement is work. The $joule (J)$ is the SI unit of work, defined as the work done by a force of $1 Newton$ in moving an object a distance of $1 metre$ in the force's direction.

$W = F \times d \times \cos (θ)$ where $F$ is the force, $d$ is the displacement. All are having units in SI units itself.

The factors affecting the work done on a body are force, displacement and the angle between force and the displacement. Force is described as a push or a pull that can modify the velocity and acceleration of any mass object. Force is a vector quantity If the force acting on an item is zero, regardless of whether the object is in a dynamic or static state, the force does no work. Displacement is a vector quantity that represents the smallest distance between an object's starting and final positions. Depending on the direction of displacement of the item with regard to the force, the work done by the force might be positive, negative, or zero.

When a force moves an object in same direction as the force, the work done is positive. The motion of a ball falling towards the earth, with the displacement of the ball in the direction of gravity, is an example of this type of work.
When force and displacement are in opposite directions, it is presumed that the work is negative. When a ball is thrown upwards, the displacement will be upwards; nevertheless, the force will be downwards due to gravity. The total work done by the force on the object is nil if the direction of the force and the displacement are perpendicular to each other. When we push forcefully against a wall, for example, the force we apply to the wall does not do any work since the wall's displacement equals to zero.

Can work done be positive, negative and zero? Explain.

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