Heat and Thermal Energy
If you have a pure glass of ice water, consisting of ice cubes floating in water, its temperature would be
0 degrees Celsius
Celsius boiling point
100 degrees Celsius
Kelvin Scale Freezing Point
273 K
Before ice can form on a lake, all the water in the lake must be cooled to
4 degrees Celsius
Heat travels from an object with ______ temperature to an object with ______ temperature
High; low
Fluids do not _______ well
Conduct
Heat travels best through a solid by
Conduction
Heat transfer through the motion of a fluid (liquids, gases, plasma)
Convection
The form of heat transfer that takes place in a house heated by forced air
Convection
Natural processes tend to move toward greater
Disorder
A 100% efficient engine would produce no increase in
Entropy
As temperature increases, solids and liquids
Expand
Hot water evaporates
Faster
Convection occurs in _____ that are warmer at the bottom
Fluids
Energy that travels spontaneously from a warm object to a cold object
Heat
Heat to melt 1 kg of a substance, heat given off by 1 kg of a substance when freezing
Heat of fusion
Heat to vaporize 1 kg of a substance, heat given off by 1 kg of a substance when condensing
Heat of vaporization
The moderate temperature of islands has much to do with the
High specific heat of water
If an object radiates more energy than it absorbs, its thermal energy and temperature
Increases
When a closed tin is heated, the pressure inside it ________ because molecules move _________ and hit the tin walls more often
Increases; faster
Heat energy is measured in units of
Joules, cals, Cals, BTUs
A food calorie is a
Kilocalorie
A decrease in temperature is a result of a decrease in the ________ of the atoms or molecules
Kinetic energy
If you measure a plot of land with a steel tape on a cold day, your measurement of the plot will be
Larger than actual
Heat engines convert thermal energy into
Mechanical energy
Thermal energy all goes to making/breaking bonds, between atoms, no change in temperature
Melting, freezing, vaporization, condensation
Compared to other substances, substances with a high specific heat will cool
More slowly
A substance melts when the _________ of its atoms or molecules is increased
Potential energy
Earth loses heat to outer space mainly by
Radiation
Heat transfer through electromagnetic waves
Radiation
Heat travels in a vacuum by
Radiation
The silver coating on the glass surface of a thermos bottle reduces energy transferred by
Radiation
Natural processes go in the direction that maintains or increases the total entropy of the system
Second Law of Thermodynamics
Energy transfer by convection is usually not found in
Solids
The heat needed to raise the temperature of 1 kg of a substance to 1 K
Specific heat
Measure of the average kinetic energy of the molecules in a substance
Temperature
Total energy of molecules in a substance
Thermal energy
Which type of change requires more energy for the same substance?
Vaporization
It takes more energy to
Vaporize
In an engine, the difference between the heat put in and the heat discharged will appear as
Work
The total increase in thermal energy of a system is the heat added to it minus the _____ done by it
Work
