Lesson 2 - Thermal Energy Transfers

gases

Radiation can occur in solids, liquids, and __________.

specific heat

The amount of thermal energy it takes to increase the temperature of 1 kg of a material by 1 °C.

convection current

The movement of fluids up and down in a cycle because of convection is called a _________ __________; these currents cause patterns in Earth's climate.

vacuum

The only way for thermal energy to travel from the Sun to Earth is through radiation; that is because radiation is the only way for thermal energy to travel through the __________ of empty space.

conduction

The transfer of thermal energy between materials because of collisions between the particles.

fluids

The transfer of thermal energy by the movement of particles from one part of a material to another is called convection; this occurs in __________ - liquids and gases.

radiation

The transfer of thermal energy from the one material to another by electromagnetic waves.

low

Thermal conductors have a __________ specific heat.

transferred

Thermal energy can be __________ from one object to another by radiation, conduction, and convection.

high

Thermal insulators have a __________ specific heat.

cooling

Water has a high specific heat, which makes this liquid good for __________.

collide

When particles that have different kinetic energies __________, the particles that have more kinetic energy transfer energy to the particles that have less kinetic energy; in this way, the average kinetic energy, or temperature, of the materials changes.

Metals

__________ are good thermal conductors because they have electrons that move easily, so they often collide with other particles and transfer kinetic energy easily.

Nonmetals

__________ are good thermal insulators because their electrons do not move easily, so compared with thermal conductors, few collisions occur between electrons and atoms of insulators.

thermal

All objects, even ice cubes, radiate __________ energy.

thermal expansion

An increase in a material's volume when the temperature is increased is called __________ __________ ; this occurs because particles spread out as their thermal energy increases.

hot

A car that has been outside on a sunny summer day will be __________ inside.

thermal contraction

A decrease in a material's volume when the temperature is decreased is called __________ __________; this occurs because particles get closer together as their kinetic energy decreases.

thermal insulator

A material through which thermal energy does not flow easily.

thermal conductor

A material through which thermal energy flows easily.

mechanical

Because kinetic energy is being transferred, __________ energy is also being transferred.

equal

Conduction does not stop until the thermal energy of all the particles that are in contact is __________.

density

Convection occurs, in part, because of differences in __________, due to thermal expansion and thermal contraction in different parts of a material.