Before Video: Heat
What is heat?
Heat is the transfer of thermal energy from one object to another.
What is cold?
Cold is just where there is less thermal energy.
Heat?
Transfer of thermal energy from one object to another or one region to another.
Density?
Measure of the mass per unit volume; degree of compactness of a substance.
What is the difference between heat and thermal energy?
Thermal energy is the energy contained within a system due to the motion of the particles. Heat is the transfer of thermal energy from a warmer system/object to a cooler system/object.
What are the 3 ways heat can be transferred?
Conduction, convection, and radiation
What is being measured when we take the temperature of something?
We are measuring the average kinetic energy of the atoms/molecules in a substance.
Thermal Energy?
Energy contained within a system responsible for its temperature due to the motion of the particles.
Temperature?
Measure of the average kinetic energy of the atoms in a substance.
When the temperature of an object decreases, what has happened?
The particles (atoms/molecules) that make up that object are moving slower. Heat has been transferred from the object to its surroundings or to another object.
Do all materials respond to heat the same way? Give an example as part of your answer.
No, the chemical composition of the material and the amount of material affects the amount of heat the material will hold.
Example, it takes more heat to raise the temperature of water than it does to raise the temperature of a metal. It would take more heat to raise the temperature of water in a bathtub full of water compared to a cup of water.
What are some real-world examples of how we use our understanding of heat to solve a problem?
Examples from the video include puffy jackets, emergency blankets, solar cookers, clothing irons, hot air balloons, fans in computers, and freezing a tongue to a pole.
Conduction?
Transfer of thermal energy through direct contact.
Circulating?
Moving continuously through a closed system.
What factors determine the thermal properties of a material?
The amount of material (mass) and its composition (what it’s made of).
How does the heat from the sun warm the earth?
Heat is transferred from the sun to Earth by radiation, because there is no medium (solid, liquid, or gaseous material) in space. The Sun emits light, and light energy is a form of electromagnetic radiation. The light energy warms the molecules of the atmosphere, the heat is then transferred by conduction.
Note: the Sun emits all forms of electromagnetic radiation except gamma rays. Visible light is probably the most obvious form of electromagnetic radiation
Mixture?
A mixture is made when two or more substances are combined, but they keep their own properties and can be separated easily.
Imagine mixing skittles and full size marshmallows, the individual components (skittles and marshmallows) could easily be separated using a filter and each component of the mixture ( skittles and marshmallow ) doesn't change.
Convection?
Transfer of thermal energy through circulation of fluids.
Waves?
Disturbance or oscillation that travels through space-time accompanied by a transfer of energy.
Why was Dr. Jeff correct in saying that “convection is … used to heat our homes”?
Whatever heating method is used (gas, electric, fire, etc.) heats the air, causing the air molecules to move faster closer to the heat source. As the molecules gain more energy, they vibrate more and spread out, which makes those particles less dense, so they rise. As they get further from the heat source, the particles move more slowly, are closer together, and become more dense, so they sink. This process continues over and over causing the air molecules to circulate.
Which will have a HIGHER temperature reading--a thermometer inside a mitten laying on a table or a thermometer laying on the same table in the same room conditions?
Both thermometers will have the same temperature. Because there is no additional heat source, there will be no change in temperature. The mitten is an insulator, but it does not produce heat.
Solution?
is a homogeneous mixture where one substance, called the solute, is dissolved in another substance, called the solvent
Example: Saltwater from the ocean, like at the beach
Radiation?
Transfer of thermal energy through waves.
Which has greater heat capacity—iron, tin, or bismuth? Why do you say this?
Bismuth, because when three cubes of the same mass were heated and dropped into the same temperature water, the water the bismuth cube was dropped in heated up much less than the water with iron or tin. A substance with a high heat capacity heats up and cools down more slowly.