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Law of conservation of mechanical energy

“The total mechanical energy of a system is constant, if the internal forces doing work on it are conservative and the external forces do no work”.

 

Verification:

Law of conservation of energy in case of freely falling body.

Conservation of mechnical energy (i2tutorials)

 

Let a body of mass ‘m’ falls from a height ‘h’ above the ground as shown in figure.

 

When the body is at the point A:

Initial velocity V0 is zero

 Conservation of mechnical energy 1 (i2tutorials)                                                    

 

When the body is at point B :

Suppose at point B, the body has velocity VB

Conservation of mechnical energy 2 (i2tutorials)

 

When the body is at point C :

Suppose at point C, the body has velocity VC

  Conservation of mechnical energy 3 (i2tutorials)              

 

From equations (1), (2), & (3) the total mechanical energy of the body at any point is constant.

Hence, the law of conservation of energy is verified in case of freely falling body.