Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information.... |
Home Conservation Laws Conservation of Energy Examples Heating a swimming pool | |||
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Heating a swimming poolIf electricity costs 3.9 cents per MJ (1 MJ = 1 megajoule = 106 J), how much does it cost to heat a 26000-gallon swimming pool from 10 °C to 18 °C? Converting gallons to cm3 gives
Water has a density of 1 gram per cubic centimeter, so the mass of the water is 9.8 × 107 g. One joule is sufficient to heat 0.24 g by 1 °C, so the energy needed to heat the swimming pool is
The cost of the electricity is (3.3 × 103 MJ)($0.039/MJ)=$130.
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Home Conservation Laws Conservation of Energy Examples Heating a swimming pool |