In some of our previous articles of the series we talked about motion, force, and gravitation. Today we are going to discuss about a scientific term “work”.
In our daily life, we are very familiar with the term ‘work’. We all do different work. Even all living things do work in their limited manner like human beings communicate through a multiple medium as speaking, writing & signing etc. travel from one place to another, arrange for food and look for shelter etc. Animals do the same kind of work like arranging food migrating and making shelters, but they didn’t communicate like human beings and plants don’t make their shelters, neither they move from one place to another or communicate like human beings, but they make food for themselves. All living things do work, but all living kingdoms have their limitations and freedoms according to their needs to carry out any particular task.
In physics, work is not anything that we understand from the observation in our daily life. Physics define it very concisely. It says, “work is a product of applied force and displacement”.
W = Fs
- F = Force
- S = Displacement
Which means, work will only be done, if any force in action makes the object travel some distance. For example, placing book from one place to another, is a work. Travelling distance, moving object by pushing, pulling or throwing is work whereas, in real life reading book is work but in physics, no matter how much you read, it will never be considered any work done. Another example is sleeping. Sleeping is work in real life, whereas while sleeping we stay at a single place and don’t cover any displacement, it’s not a work in physics.
Unit of work is derived from its coefficients. Such as unit of force is Newton (N) and unit of displacement is meter (m), hence unit of work is Nm. In international System of Unit (SI), Joule is used as a unit of force after the name of English physicist James Prescott Joule.
As we can see, both the coefficients of work are vector quantity and their dot product is the work. We also know that dot products of two vector quantities always result in a scalar quantity. Hence, we can conclude that, work is a scalar quantity, thus it has only magnitude.
At the end of this article, let’s talk about two different types of work.
- Positive work: when object is displaced in the direction of force, it is said a positive work is done.
- Negative work: when object is displaced in the opposite direction of force, it is said a negative work is done.
That’s enough for now, in our next article, we will discuss about energy. Until then try to come with at least one example of positive and negative work and write in the comment box.
