The law of thermodynamics states that energy can't be created or destroyed. two natural sources of energy on earth are the

So we need to put in the correct words to fill in the blanks. The FIRST law of thermodynamics states that energy can't be created or destroyed. It is a formulation of the law of conservation of energy modified for thermodynemical systems. Two natural sources of energy on Earth are the solar and wind. Also geothermal energy and hydropower are natural sources of energy.

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This is what a calorimeter is used for simpler ex, to measure calories in food.