Question

Prove and State the the law of conservation of energy. Explain in detail.

Answer 1

Law of conservation of energy: 

Law of conservation of energy states that Energy is neither be created or nor destroyed. Energy can be changed only from one form to another. in other words we can say " the total energy of a closed system always remains constant".


This law is valid in all situation and for all type of transformations.


Let's consider an example.

an object of mass, "m" be managed to fall freely from a height, "h".
at the begin, potential energy is "mgh" but kinetic energy is zero.



Why the kinetic energy zero?

It is zero because its velocity is zero. therefore, the total energy of the object is "mgh". since it falls, its potential energy will change to kinetic energy. if "v" is the velocity of the object at a provided instant,  the kinetic energy would be 1/2m². Since the fall of object continues, would decrease potential energy whereas the kinetic energy would increase. when the object is about to come the ground the ground, then "h" = 0 and "v" will be the greatest. so, the kinetic energy will be the largest and potential energy the smallest. 

However, the sum of the potential and kinetic energy would be similar at all points.


Kinetic energy + potential energy = constant.

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Hope it helps ^_^

Answer 2

Hi there !!!!

Law of Conservation of Energy states that Energy can neither be created nor be destroyed,It can be transferred from one object to another and can be transformed from one form to another form.

Mechanical Energy = Potential Energy + Kinetic Energy


First of all lets take a look at the two types of Mechanical Energy :

Do you know what are the types of mechanical Energy ?

Answer :

Two Types of Mechanical Energy are :
<>Potential Energy
<>Kinetic Energy

⇒Potential Energy :-
Potential Energy is the Energy possessed by a body by virtue of its height or by virtue of its strained configuration
Potential Energy = mgh , m = mass , g = acceleration due to gravity , h = height

Can you list some examples ??

Here are some examples ....

A stretched rubber band , a winded spring , Water stored in a dam , Bow and Arrow.

⇒Kinetic Energy:-
Energy possessed by a body by virtue of its motion.
All moving bodies possess Kinetic Energy
Kinetic Energy = 1/2 mv² , m = mass , v = velocity

Here are some examples .....

Running athlete , racing car , coconut falling from a tree etc ....

Lets check whether the Law of Conservation of Energy is correct or not :


SO ,
Lets take an example of a Freely Falling Body : -

At the maximum height , the body possess maximum Potential Energy and at this same point , the body possess zero Kinetic Energy , as it is not in motion.

As it moves down , potential energy of the body decreases [ height is decreasing , so P.E is also decreasing ]and Kinetic Energy increases [as the body is in motion ].

At the lowest point , before touching the ground , the body possess maximum Kinetic Energy and zero Potential Energy.
After touching the ground , the energy gets converted to Sound , light or any other forms of energy

But at all the points the energy remains constant.

That is ,
Potential Energy + Kinetic Energy = a Constant

mgh + 1/2mv² = a constant

After touching the ground , the mechanical energy gets converted to Sound , light energy or any other forms of energy