Heat Transfer
This is the transfer of thermal energy through direct contact between particles.
What is conduction?
This quantity measures the average kinetic energy of the particles in a substance.
What is temperature?
A device that changes thermal energy into mechanical energy is called this.
What is a heat engine?
When temperature increases, this average property of particles also increases (three words).
What is average kinetic energy?
All objects emit this type of radiation because of their temperature.
What is electromagnetic radiation (thermal radiation)?
This is a heat transfer in fluids (liquids and gases) that occurs when warmer, less dense fluid rises and cooler, denser fluid sinks is called this.
What is convection?
Which temperature scale has its zero point at absolute zero? Give the scale name and the symbol for absolute zero temperature.
What is Kelvin; absolute zero is 0 ∘K
In an internal combustion engine, this part transforms thermal energy into mechanical energy by moving up and down.
What is a piston?
When a substance is heated, its particles spread out creating more volume. What happens to the mass of the substance?
What is the mass remains the same?
Why does your hand feel cold when you take a bottle of cold water out of the refrigerator (name the heat transfer method)?
What is conduction? — your hand loses heat to the cold bottle by direct contact; the bottle conducts heat away from your hand.
The type of heat transfer that does not require matter and that allows you to feel the warmth from a stovetop without touching it.
What is radiation?
This is what most materials do this when heated (short phrase).
What is expand (thermal expansion)
List three examples of common heating appliances.
Coffee maker, clothes iron, curling iron, etc.
(Teacher decides if answers are correct)
Define thermal expansion and thermal contraction.
Thermal expansion: increase in size or volume when heated. Thermal contraction: decrease in size or volume when cooled.
What is the lowest possible temperature called, and give its numerical value.
What is absolute zero, 0 ∘K(zero Kelvin)?
Explain why your hand gets cold when taking a water bottle out of the refrigerator.
What is conduction?
Explain one similarity and one difference between temperature and thermal energy.
Similarity: both relate to particle energy
Difference: temperature is average kinetic energy per particle; thermal energy is total kinetic + potential energy of all particles.
Describe the role of the compressor in a refrigerator and explain how it affects the coolant.
The compressor compresses the coolant, raising its pressure and thermal energy, which then moves through the system (compressor increases coolant temperature and pressure).
In an experiment, bars of different metals are heated to the same temperature. Predict how their lengths change and write a one‑sentence statement describing the outcome.
All bars increase in length and volume; different metals expand by different amounts depending on their coefficients of thermal expansion.
A hot iron cools down after being turned off. Explain in one sentence why it cools using the idea of thermal energy transfer.
The iron cools because thermal energy is transferred from the warm iron to the cooler surrounding air and objects (heat flows from warmer to cooler)
A metal spoon in a hot pot gets hot at the handle. Identify the dominant heat transfer method and explain why metals behave this way compared to wood.
Conduction; metals are good thermal conductors because their particles transfer kinetic energy quickly. Wood is an insulator and slower to conduct heat.
Every material has a value that describes how hard it is to change its temperature. Name this property and explain why the ocean stays relatively cool in summer because of it.
What is specific heat; High specific heat means temperature changes slowly; the ocean stays cool because water has a high specific heat.
Explain in sequence how a basic heat engine (or internal combustion engine) converts chemical energy (from fuel) into mechanical energy, naming at least two steps or parts involved.
Fuel combusts → chemical energy released becomes thermal energy → thermal energy increases gas pressure in cylinder → high-pressure gas pushes piston → piston motion becomes mechanical work. (Also mention intake/mixing in cylinder, compression, combustion/expansion, exhaust.)
Explain why a bimetallic coil is used in a thermostat and how that causes the thermostat to turn heating/cooling systems on or off.
A bimetallic coil has two metals with different expansion rates; when temperature changes, the coil bends and mechanically switches the thermostat to control heating/cooling.
Describe how a liquid thermometer works and explain why a thermometer measures temperature but not total thermal energy.
A liquid thermometer uses a liquid that expands when warmed; the liquid rises in a tube indicating temperature. It measures temperature (average kinetic energy effect on the liquid) but not total thermal energy, because it does not account for the number of particles or potential energy in the object.