How to Distinguish between temperature and thermal energy.
How to Describe three different methods of heat flow.
What are the first two laws of thermodynamics. What are the limitations placed on heat flow by the first two laws of thermodynamics.
How does energy flow in heat engines and refrigerators?
1. What is the difference between heat and temperature?
Heat energy is the total amount of energy contained by all of the particles within an object.
Temperature is the average kinetic energy contained by any one particle with that object.
2. Consider a small cup of boiling water and a bathtub full of cold tap water. Which one has the higher temperature? Which one has greater heat energy? Explain your answers.
A small cup of boiling water is most certainly hotter to the touch than a bathtub of cold water. However, a tub of water contains many times more water molecules than a small cup of boiling water and, thus, contains a greater collective amount of heat energy than a small cup of boiling water.
List, describe, and provide an example of the 3 ways in which heat energy is transferred.
a) Conduction – the transfer of thermal energy by collisions between particles , such as heat being transferred from a bowl of hot soup to a metal spoon
b) Convection – the transfer of thermal energy in fluids through the large-scale movement of the substance, such as a warm air mass rising up from Earth’s surface into the atmosphere
c) Radiation – the transfer of thermal energy by electromagnetic waves, such as heat energy from the Sun traveling through space to reach the Earth
3. Compare conductors to insulators. What types of materials make good conductors? What types of materials make good insulators?
Conductors are substances that easily transmit heat energy. Most metals are good conductors.
Insulators are substance that slow the transmission of heat energy. Most non-metals are good insulators.
4. List, explain, and provide an example of the 1st and 2nd laws of thermodynamics.
1st law of thermodynamics – the increase in thermal energy of a system equals the amount of work done on the system plus the heat transferred to the system; this is essentially the same as the law of conservation of energy (energy is neither created, destroyed, or lost)
2nd law of thermodynamics – it is impossible for heat to flow from a cooler object to a warmer object; holding an ice cube in your hand results in heat being transferred from your hand (the warmer object) to the ice cube (the colder object)
Homework and study
Practice pp. 186-187 #1,2,5-10
Thermal Energy Writing Journal pp. 39-42