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Question
State and explain the law of conservation of energy with an example.
Solution
Law of conservation of energy: Total energy of this universe is conserved (is constant). Energy cannot be created nor be destroyed. But can be transformed from one form to another.
Example - In an electric bulb, when the electrical energy is converted into light energy, some energy is wasted in the form of heat. Although some energy is wasted in the form of heat but the total energy of the system remains same.
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RELATED QUESTIONS
Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it a violation of the law of conservation of energy?
Explain how, the total energy a swinging pendulum at any instant of time remains conserved. Illustrate your answer with the help of a labelled diagram.
The following data was obtained for a body of mass 1 kg dropped from a height of 5 metres :
|
Distance above ground |
Velocity |
| 5 m | 0 m/s |
| 3.2 m | 6 m/s |
| 0 m | 10 m/s |
Show by calculations that the above data verifies the law of conservation of energy (Neglect air resistance). (g = 10 m/s2).
