WORK, ENERGY AND POWER
Contents
1. Overview
Definition of Work
2. Elaborations
3.Definition of Energy
Kinetic Energy
Potential Energy
4.Elaborations
5.Definition of Power
Definition of Work Energy Theorem
Law on the Conservation of Energy
Energy cannot be Produced or Lost
Mass and Energy Equivalence
Law on the Conservation of Energy
Energy cannot be Produced or Lost
Mass and Energy Equivalence
6. Elaborations
7. Collision
Elastic Collisions
Inelastic Collisions
8. Elaborations
9.Elastic Collision in One dimension
10.Elastic Collision in One dimension
12.Conservative and on-conservative forces
Conservative forces
Non-conservative forces
Non-conservative forces
Example Questions
Important Extra Questions
NCERT- Q&A -SOLUTIONS
13.Very Short Answer Type
14.Very Very Short Answer Type
15 Long Answer Type
16. Numerical Problems
17.Value-Based Type
1
Overview
Here is a quick overview of some of the important basics of work, energy and power.
Definition of Work
| Definition | When a force applied to an object moves that object, then it is called as Work |
| Formula | W = F × d |
| SI Unit | The SI unit of work is labelled as joule (J). |
Definition of Energy
| Definition | Energy is defined as the capacity to do work. |
| Formula | P.E. = mgh |
| Si Unit | The SI unit of energy is called as joules (J) |
Definition of Power
| Definition | The rate at which work is done i.e. the energy converted can be defined as Power. |
| Formula | P = W/t |
| SI Unit | The SI unit of power is called watt (W). |
Definition of Work
Work is said to be achieved as a movement of a body or entity is caused by the use of external force. Work is also interpreted as an action in the direction of the applied force.
W = F × d
For example, a force of 40 Newtons (N) that moves the object 5 metres in the same direction as the force does 200 Joules (J) of work.
The SI unit of work is taken as joule (J).
Example
An object is pulled across the surface by a 100 N force which is acting parallel to the surface horizontally. Calculate the amount of work done which is performed by the force in the moving object through a distance of 8 m
Solution:
Given, F = 100 N
d = 8 m
Since F and d are present 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]
