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Temperature, Heat, Thermal Expansion , and Heat Transfer. Physics I. Temperature. defn : what a thermometer reads Average kinetic energy reading of a substance Fahrenheit, Celcius , Kelvin scales. Temperature Conversions. °F = (1.8 x °C) + 32 °C = (°F – 32) ÷ 32 K = °C + 273.15.
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Temperature, Heat, Thermal Expansion, and Heat Transfer Physics I
Temperature • defn: what a thermometer reads • Average kinetic energy reading of a substance • Fahrenheit, Celcius, Kelvin scales
Temperature Conversions °F = (1.8 x °C) + 32 °C = (°F – 32) ÷ 32 K = °C + 273.15
Heat • Defn: transfer of energy from one object to another due to difference in temp. • Coffee mug examples • 80°C coffee sitting on counter of kitchen that is 26°C – what happens? • What if cold (5°C) pop can sitting on the counter of same kitchen?
Heat • Internal Energy • A substance contains internal energy… NOT heat • There is more internal energy in a bathtub full of cold water than a red-hot pin (due to the higher number of molecules; therefore, bathtub has more kinetic energy) • But! Heat flows from red-hot pin to tub water
Measuring Heat Heat is a form energy (Joules) Calories:
Specific Heat Defn: quantity of heat required to change temperature of a unit mass of substance by 1° Water (discussion – see map next slides)
Thermal Expansion • As Temp. decreases => Substances contract (become more dense) • Except Water! • H2O MOST dense at 4°C • From 4°C to 0°C, water expands (becomes less dense) • Which is why ice floats
Conduction • Heat transferred by successive collisions of atoms • Good conductors of heat and electricity: • Metals - #1 Ag, #2 Cu, #3 Al… • Poor conductors: • Wool, wood, styrofoam • = insulators • In February you drive by a house with snow on its roof. Does the house have good insulation or poor? Explain.
Convection Heat transferred due to motion of fluid Theory behind plate tectonics
At night or during day? Explain. What happens during other half of earth rotation? Explain.
