[Physics Class Notes] on Work and Power Pdf for Exam

Every day of your life you move through systems of power and that these powers make you perform your work. So, are work and power interrelated concepts? Are they interdependent on each other for their functioning? When you see two weightlifters, lifting the rings you will see both are performing the same work but their speed might differ. So what is that which makes them work at a different speed? All your questions will be answered by the end of this article. The faculties have compiled this important concept of physics in this article and try to make you understand them in a simple way. 

In this particular article, we shall be learning about the following concepts – 

• Wok and power – an introduction

• What is work?

• What is power?

• Difference between work and power

• Fun facts

• Frequently asked question

Let’s get started!

What is Work?

Most often, you use the term ‘work’ to express doing some task.  It can be either reading a book or sitting at your work-station to complete a job on the computer.  However, the scientific term work done is not related to the stationary task.  Science defines work as a task done when a force acts upon a body that produces displacement in it.  In simple words, work is not complete until and unless force is applied, which moves an object.  The standard unit of work is the Joule denoted as (J).  You can define one Joule of work done as the amount of work done when 1 Newton of force brings about a displacement of 1 meter in the direction of the applied force.

You can measure the work you do as positive, negative, or zero. 

Work done is positive when the direction of force acting on the object and displacement of the object both are in the same direction.  For example: Kicking a ball Work done is negative when the direction of force acting on the object and displacement of the object are in the opposite direction.  The angle between displacement and force is 180⁰.  For example, work is done by gravity on a ball thrown in the upward direction.

Work done is zero, when the direction of the force acting on the object and displacement of the object are perpendicular to each other. The angle of displacement and force is 90⁰.  For example, work is done by gravity when a box is moving horizontally.

Power

The scientific definition of power is the rate of doing work. Power is the energy you need to displace an object in a given time.  You need the energy to stop a moving object, raise an object against gravity, or move an object having a certain velocity.  In simple language, power is the proportion of work done in one unit of time.  The standard unit of measurement of power in Watts and kilowatts is denoted as (W) and (kW) respectively.  You can define one Watt as 1 Joule of work done per second. It means that when a body works at the rate of 1 Joule (J) per second, then its power becomes 1 watt, (W).  

Formula: Difference Between Power and Work

Now, let us look at the formulas that differentiate work from power.

Total Work Done (W)  = Power (P) x Time (t)

Or

Work = Force x Displacement cos  (Fd cos )

(Here,  is the angle between force and displacement)

Power (P) = [frac{text{Total Work Done (W)}}{text{Time(t)}}]

It would be easy for you to distinguish between work and power when you study the difference between work and power in tabular form.

Work and Power Difference in Tabular Form

Fun Facts on Work and Power

1. If you are kicking a ball, your work done is positive.

2. If you are sitting in the classroom, listening to lectures, the work done is said to be zero.

3. Industries, households, commercial establishments use 1 Kilowatt(kW) of power.

4. Force and displacement are both vector quantities, but their dot product gives work done, which is a scalar quantity.