Basics of work done

A trip to the market

On Sunday, Ram’s father asked him to lift the water can and stand for 5 minutes

Obeying him, Ram lifted it for 5 minutes and stayed there.

Ram exclaimed how much he worked but to his surprise his father said that he did no work at all !!

Ram was confused, and could not understand why his father was saying so

So, he asked his father to explain the reason behind this remark

Let’s see what did Ram come to know about work

By intuition we know that we do work when we move something from its position

The scientific definition of work is also similar to this, let’s see what science says about work

Work

Work is said to be done when "applied force produces displacement in the direction of force"

This means, we need two parameters to define amount of work done

We need the amount of applied force

And we need the displacement

Together these parameters give work done as above

So, amount of work done is given by above relation

The SI unit of work is Joule (J)

The SI units of force and displacement are Newton(N) and meter(m) respectively

This means that if 1 N of applied force produces a displacement of 1 m then 1 J of work is said to be done

One thing to be noticed is that displacement is essential for work to be done

Although a body may travel some distance, but it’s displacement may or may not be zero

In case the starting and final positions of a body are the same, then displacement is zero

So, work done is also zero !!

Also, if in case a force is applied but no displacement occurs

Then also NO work is done !!

Revision

Work is said to be done when applied force produces displacement in the direction of force applied

Work done is the product of force applied and displacement of the body

If either any one parameter is zero, then work done turns out to be zero

Work done always requires displacement and NOT distance covered by the body

The End