Cold water at a temperature of 15 degree Celsius enters a heater, and the resulting hot water has a temperature of 61 degree Celsius. A person uses 120 kg of hot water in taking a shower. (a) Find the energy needed to heat the water. (b) Assuming that the utility company charges $0.10 per kilowatt · hour for electrical energy, determine the cost of heating the water. (1KWh = 3.6 x 10^6 J)
Latent heat and phase change
A physical process in which a conversion among the basic states or phases of matter, i.e., solid, liquid, and gas takes place under the effect of a certain temperature and pressure is referred to as a phase change. Generally, the phase change of a substance occurs when heat transfer takes place between the substance and its surroundings. Based on the direction in which heat transfer takes place, different types of phase changes can occur.
Triple Point of Water
The branch of physics in which observer deals with temperature related properties is called thermodynamics.
Boiling Point of Water
Everyday examples of boiling is, boiling milk, heating water. One would have observed that when we heat water it goes through various stages and at one point bubbles show in water, and water keeps splashing with bubbles bursting, we in layman terms say that water is boiling.
Freezing Point of Water
In general, the freezing point of water is 0° Celsius, or 32° Fahrenheit. This is the temperature at which water will ordinarily change from its liquid state to its solid state (ice). However, there are certain conditions that can affect the freezing point of water. For example, a liquid may be supercooled or contain impurities so that it does not freeze at the ordinary freezing point.
Cold water at a temperature of 15 degree Celsius enters a heater, and the resulting hot water has a temperature of 61 degree Celsius. A person uses 120 kg of hot water in taking a shower.
(a) Find the energy needed to heat the water.
(b) Assuming that the utility company charges $0.10 per kilowatt · hour for electrical energy, determine the cost of heating the water. (1KWh = 3.6 x 10^6 J)
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