Question

What are the different types of work?

Answer 1

Work:

1. Work is defined as a force acting on a body or item that causes the displacement of that body.
2. It can be expressed as the dot product of force as well as the displacement.
3. The SI unit of work is joules $\left(J\right)$.

Mathematically, it can be expressed as;

$W=Fs\cos \theta$

Where,

$F$ represents force.

$s$ represents displacement.

$\theta$ is the angle between force and displacement.

Types of work:

The different types of work are as follows:

1. Positive work: Work is said to be positive $\left(+\right)$, if the body is displaced in the direction of the force i.e. when $\theta =0°$. For instance, the motion of a body falling towards the ground when the direction of the body is in the direction of the gravitational force. Then the work done by force of gravity is positive. The work done is positive $\left(+\right)$ when the angle is acute (less than $90$ degree).
2. Negative work: Work is said to be negative $\left(-\right)$, if the force and the displacement are in opposite directions i.e., when $\theta =180°$. For instance, if a body is thrown in an upward direction, however, the force due to the gravitational pull is in the downward direction. Work done by force of gravity is negative. The work done is negative $\left(-\right)$ when the angle is acute (more than $90$ degree).
3. Zero work: Work is said to be zero if the force and the displacement are perpendicular to each other i.e., when $\theta =90°$. For instance, if we push hard against a wall, then the force exerted on the wall does not work, because in such a case, the displacement of the wall $s=0$.
4. By looking at the expression for work ($W=Fs\cos \theta$), F and s have the same magnitudes, the quantity of work would vary depending on the angle between them.