עמוד:30

The Law of Conservation of Energy Following are three illustrations : A small wave crashing on the beach , a high wave far away from the beach , and a huge Tsunami wave . All three waves possess energy ; however , they differ in their amounts . Energy , therefore , has an amount , and in different situations the amounts of energy differ from one another in magnitude . We have seen that energy can undergo change : energy may be converted and transferred from body to body . For example , the electrical energy in a music player is transformed ( converted ) to sound energy and is transmitted to a child’s ear . The chemical energy of a missile is converted to kinetic energy , and the chemical energy of an automobile’s fuel is transferred to its engine , where it is converted to kinetic energy as well . But what happens to the amount of energy when it changes from one type to another or when it is transferred from one body to another ? The conclusion drawn from the many experiments conducted throughout the generations is that the amount of energy remains constant when it passes from one body to another or when it changes from one form to another . Despite the changes that energy undergoes , the amount of energy remains unchanged . This applies to a closed system , in other words , a system in which no energy enters from its environment and no energy escapes to its environment . This rule is called the law of conservation of energy . The law may be described as follows : 1 . Energy is not created out of nothing . 2 . Energy does not disappear . 3 . The total amount of energy is constant , and remains unchanged ; it does not increase and it does not decrease throughout the changes it undergoes . Up to now , no phenomenon has been found that contradicts this conclusion ; therefore , it is accepted as a law of nature . The law of conservation of energy : The amount of energy remains constant during energy changes . Energy is not created out of nothing . This is true when referring to a closed system : no energy enters from its environment and no energy escapes to its environment .

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