What is Meaning of Potential
Potential means having the capacity to do something
Example
A child has potential to score good marks in exams
A brick has potential to hurt us
What is Potential Energy
Energy stored in a body because of its position or change in shape is called Potential Energy
Example 1
brick lying at ground does not have potential energy
But if we pick up a brick it has potential energy
Example 2
An arrow attached to bow has no potential energy
But if we stretch the bow, it has potential energy
Different Types of Potential Energy
This energy is of 2 type
Gravitational Potential Energy-
Potential Energy due to position of an object
Example - A raised brick, Brick lying on terrace
Elastic Potential Energy-
Potential Energy due to change in shape
Example - Stretched Rubber String, Stretched bow
How does a raised brick have Potential Energy?
Suppose brick is lying at ground
It currently has no potential energy
We pick it up applying our muscular energy
We position it towards our feet
At this point of time,we have spent energy in picking up the brick
This energy is stored in the brick in the form of potential energy
(If we let go the brick at this point of time,it has the potential to hurt our feet)
Hence,we say that brick has potential energy because of its relative position compared to our feet
Potential and Kinetic Energy in birds
A bird sitting on a tree branch has potential energy
But when it flies, it has both potential and kinetic energy
Note-Sum of Potential and Kinetic Energy is called Mechanical Energy
How to Calculate Gravitational Potential Energy
We know that Gravitational Potential Energy is due to Position of body lying at a height above earth
Potential Energy is equal to Work done by body in moving against gravity to reach at that height
So
Potential Energy = Work Done in Moving against gravity
Potential Energy = Force × Distance
Potential Energy = Mass × Acceleration × Distance
Potential Energy = Mass × Acceleration due to gravity × Height
Potential Energy = m × g × h
Questions
Questions
Example 11.5 - Find the energy possessed by an object of mass 10 kg when it is at a height of 6 m above the ground. Given, g = 9.8 m s –2.
Example 11.6 - An object of mass 12 kg is at a certain height above the ground. If the potential energy of the object is 480 J, find the height at which the object is with respect to the ground. Given, g = 10 m s –2 .
