Heat transfer Flashcards
What are the three mechanisms for heat transfer?
Conduction, convection, and radiation
True or False: Heat and temperature are the same thing.
False
Define heat in the context of thermal energy.
The total energy in a substance due to the movement of the molecules.
Define temperature in the context of thermal energy.
A measure of the average energy of individual molecules in a substance.
What is conduction?
The transfer of thermal energy through direct contact.
What is convection?
The transfer of thermal energy through the movement of a liquid or gas.
What is radiation?
The transfer of thermal energy through thermal emission.
How does conduction occur in solids?
Hotter atoms vibrate more and pass energy to their colder neighbors.
Why do different metals conduct thermal heat at different rates?
Because of their atomic structure and the movement of free electrons.
Fill in the blank: Copper is ______ times better at conducting thermal energy than water.
600
Fill in the blank: Air is ______ times worse at conducting heat than water.
25
What causes convection currents in fluids?
The hotter fluid becomes less dense and rises.
How does a radiator utilize convection?
It heats the air close to it, causing the air to rise and form a convection current.
What type of radiation is involved in heat transfer?
Infrared electromagnetic radiation.
True or False: Radiation requires matter to transfer energy.
False
What happens to thermal radiation from a hot body?
A hot body emits much more infrared radiation than a cool one.
What is the effect of a dark surface on thermal radiation?
A dark surface absorbs radiation better than a light surface.
Fill in the blank: A matt surface absorbs radiation better than a ______ surface.
shiny
How do transparent liquids behave in terms of thermal radiation?
Like transparent solids.
What happens when the surface of a liquid heats up?
A convection current is set up within the liquid.
How does radiation behave in gases?
Radiation passes relatively easily through gases with some absorption and re-radiation.
