Explain the law of conservation of energy .

Explanation

Law of conservation of energy : When forces doing work on a system are conservative then total energy of the system is constant i.e., energy can neither be created nor destroyed .
i.e., Total energy = (K+u) = constant form .
Explanation : Condider a body undergoes small displacement `Deltax` under the action of conservative force F . According to work energy theorem .
Change in K.E = work done `DeltaK=F(x)Deltax" " ......(1)`
but Potential energy `Deltau=-F(x)Deltax" " .....(2)`
from (1) and (2) `=DeltaK=-Deltau`
`rArrDelta(K+u)=0`
Hence (K+u) = constant
i.e , sum of the kinetic energy and potential energy of the body is a constant
Since the universe may be considered as an isolated system , the total energy of the universe is constant .