ENERGY FLOW
What are the three main ways heat is transferred?
Conduction, Convection, and Radiation
What is conduction?
Conduction is heat transfer between particles in direct contact.
What is convection?
Convection is heat transfer by the bulk movement of a fluid (liquid or gas).
What is radiation?
Radiation is heat transfer by electromagnetic waves.
What is the law of conservation of energy?
Energy cannot be created or destroyed, only transferred or transformed.
Which of these does NOT require matter to travel through: conduction, convection, or radiation?
Radiation
Which material (metal, wood, or air) is the best conductor of heat?
Metal
What happens to air when it is heated (in terms of density and movement)?
When air is heated it expands, becomes less dense, and rises.
Give an everyday example of heat transferred by radiation.
Sunlight warming your skin, or heat from a campfire felt at a distance.
In heat transfer processes, what happens to thermal energy overall (created, destroyed, or moved)?
In heat transfer processes, thermal energy is moved or transformed (it is not created or destroyed).
If a metal spoon in a hot cup becomes warm at the handle, which type of heat flow moves through the spoon?
Conduction
Why does touching a hot pan handle that is wrapped in cloth feel cooler than touching the bare metal?
The cloth reduces conduction, the handle transfers heat more slowly.
Give an example of convection in Earth’s systems (atmosphere or ocean).
Warm ocean currents transporting heat (ocean convection) or warm air rising to form weather patterns in the atmosphere.
How does radiation travel differently than conduction and convection?
Radiation travels as electromagnetic waves through empty space and does not require particles contacting or flowing; conduction and convection require matter.
What is thermal energy?
The total kinetic energy of particles in a substance.
Explain in one sentence how thermal energy relates to the motion of particles.
Thermal energy is the total kinetic energy of particles in a substance; more particle motion means higher thermal energy.
A metal rod has one end heated. Describe how temperature changes along the rod over time and why.
The temperature will be highest near the heated end and decrease along the rod toward the cooler end; over time heat conducts down the rod until a gradient (or equilibrium if held long enough) is reached because kinetic energy transfers between adjacent particles.
Explain what a convection current is.
A convection current is a circular movement in a fluid caused by heating and cooling.
If the sun warms your skin on a cool day, explain which form of energy transfer that is and why matter between you and the sun is not needed.
The sun warming skin is radiation because infrared and visible light travel through space as electromagnetic waves; no matter between the sun and you is required.
What is heat?
Energy transferred between objects because of a temperature difference.