Work Done - Definition, Formula, Derivation and Types
Work Done - Definition, Formula, Derivation, and Types
In our day-to-day life, we hear that a person is working so hard to achieve his goal, that worker is working hard to move an object from one place to another place by pushing, rolling, etc. Have you ever wondered how all that work is measured in physics to prove that to say some work is done? Let's find out the concept behind this.
What is work done in Physics?
When we apply force on an object to move from one point to another point, a change in the position of the object occurs which is called Displacement.
The work done (W) is calculated using the below formula -
Work Done (W) = Force applied to object (F) x Displacement (D)
or
W= FDCosθ - When force is applied at an angle 'θ'
Unit and Dimension of Work Done
The unit of Work done is Joule (J), and its dimension is [ML2 T-2]
Derivation Of Work Done
An example for your better understanding of the concept -
Q - A person pushes a wooden block with a force of 5N for 10m in a Straight Line. Find the work done by the person?
A - We have, Force Applied by the person = 5N
Displacement = 10m
We have the formula,
Work Done= Force x Displacement
Work Done = 5x10
= 50 Joule
Therefore, the work done by the person is 50 Joule.
Types Of Work Done
There are mainly 3 types of work done -
1. Positive Work Done
2. Negative Work Done
3. Zero Work Done
A brief explanation of types of work done -
1. Positive Work Done - When the force and displacement are in the same direction then the work done is called to be positive.
For Example - A doctor or a nurse moving a patient in a wheelchair or riding a bicycle is also a good example of positive work done.
2. Negative Work Done - When force and displacement are in the opposite direction then the work done is said to be negative.
For Example - If a ball is thrown upward in the direction, gravity pulls the ball in an opposite or downward direction. This type of work done is negative.
3. Zero Work Done - When the force is applied on the body is positive but the body doesn’t move from the position i.e. displacement is zero. Then, work done is said to be zero.
For Example - If we push or apply force on a wall but the wall does not move from its position it results in zero displacements. Then, this type of work done is zero.
FAQs (Frequently Asked Questions) Using Work Done Formula
Q1 - What is the Formula, Unit & Dimension of Work Done?
A - The formula of Work Done is -
Work Done=Force Applied (F) x Displacement (D)
Unit of Work Done is = Joule (J)
Dimension of Work Done = [ML2 T-2]
Q2 - If a ball is thrown up in the air by the force what type of work done it is?
A - Since the ball is thrown upward, the gravity force acts in opposite direction to the applied force. Hence, it is a negative type of work done.
Q3 - If the wooden block is slid on a concrete road then what type of work is done by the friction?
A - Friction force has the property to stop any object by acting in the opposite direction, hence the force applied and friction force is in the opposite direction to each other. Hence, the work done is Negative.
Q4 - If a person hit the wall with the iron rod then what type of work it is?
A - Since the wall is not moved or displaced from its position. the displacement is zero. Hence, the work done is zero in this case.