Class 11 physics work,energy and power handwritten notes
Work, Energy and Power
Work, energy and power are the most used terms in Physics. They are probably the first thing you learn in your Physics class. Work and energy can be considered as two sides of the same coin. In this article, we will learn all about the concept of work, power and energy.
Work done is generally referred in relation to the force applied while energy is used in reference to other factors such as heat. Power is defined as work done per unit time.
What is Work, Energy and Power?
Work
Definition Work is said to be done when a force applied to an object moves that object.
Formula We can calculate work by multiplying the force by the movement of the object.
W = F × d
Unit The SI unit of work is the joule (J)
Energy
Definition In physics, we can define energy as the capacity to do work.
Formula For the potential energy the formula is
P.E. = mgh
Unit The SI unit of energy is joules (J), which is named in honour of James Prescott Joule.
Power
Definition Power can be defined as the rate at which work is done i.e. energy converted.
Formula The formula for power is
P = W/t
Unit The unit of power is watt (W).
What is Work?
Work is said to be done when a body or object moves with the application of external force. We can define work as an activity involving a movement and force in the direction of the force. For example, a force of 30 newtons (N) pushing an object 3 meters in the same direction of the force will do 90 joules (J) of work.
Formula of Work
When we kick a football, we are exerting an external force called F and due to this force (kick), the ball moves to a certain distance. This disposition of ball from position A to B is known as displacement (d). This work is said to be done and can be calculated as W = F × d
Work = Force × Displacement = F × d
Unit of Work
If a force of 5 newtons is applied to an object and it moves 2 meters, the work will be 10 newton-meter. Newton meter in termed and Joules and it is the unit of Work.
Example of work
An object is horizontally dragged across the surface by a 100 N force acting parallel to the surface. Find out the amount of work done by the force in moving the object through a distance of 8 m
We know that,
F = 100 N
d = 8 m
Since F and d are in the same direction,
θ = 0, [θ is the angle of the force to the direction of movement]
W = F Cos θ
= 100 x 8 x Cos 0
= 800 J [Since Cos 0 = 1]
Related Concepts
Introduction To Work Done
Work Energy Theorem And Its Application
What is Energy?
Energy is the ability to perform work. Energy can neither be created nor destroyed. It can only be transformed from one kind to another. The unit of Energy is same as of Work i.e. Joules. Energy is found in many things and thus there are different types of energy.
All forms of energy are either kinetic or potential. The energy in motion is known as Kinetic Energy whereas Potential Energy is the energy stored in an object and is measured by the amount of work done.
Types of energy
Some other types of energy are given below:
Mechanical energy
Mechanical wave energy
Chemical energy
Electric energy
Magnetic energy
Radiant energy
Nuclear energy
Ionization energy
Elastic energy
Gravitational energy
Thermal energy
Heat Energy
Unit of energy
The SI unit of energy is joules (J), which is named in honour of James Prescott Joule.
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