Question

How is work, time and power related?

Answer 1

Hint: Work in physics can be defined as the energy absorbed when an object is moved from one place to another by applying an external force. Rate of doing work is defined as power. Thus, the difference in units of power and work is, there is a ${s^{ - 1}}$ term in the unit of power.

Complete step by step answer:
Before understanding work in physics, let us understand the topic of energy as the terms work and energy are closely related.
Energy is defined as the ability to do work.
We know, when an external force is applied on an object, work is done. This amount of work done causes a change in energy.
Therefore, In other words, the work is defined as:
It is the amount of energy transfer, when an object is displaced from one place to another, due to an applied external force part of which is applied in the direction of displacement of the body.
Mathematically, work can be denoted as the dot product of force and displacement.
$W = F.d$
$W$ Denotes the amount of work done
$F$ Denotes the amount of external force applied
$d$ Denotes the amount of displacement caused.
Unit of work done is newton-meter $(N - m)$ or joules$(J)$.
Let us consider $t$ be the time taken for work to be done. Then, work done in per unit time is given as:
$\dfrac{W}{t}$
The quantity that defines the amount of work done per unit time, is known as power.
In terms of energy, we can define power as the amount of energy converted or transferred per unit time.
Mathematically, power can be written as:
$P = \dfrac{W}{t}$
Units of power are watt $(W)$ or joules per second$(J/s)$.

Note: As work is done mathematically is the dot product of force and displacement, there comes a quantity $\cos \theta$ in the expression of work done, where, $\theta$ is the angle between the applied force and displacement. Therefore, zero or no work is done when$\theta = {90^o}$, that is force and displacement being perpendicular to each other, and maximum work is done when $\theta = {0^o}$or $\theta = {180^o}$