physical science part 1

Describe the kinetic energy changes in the particles of a substance during heating and cooling.

As a substance is heated (no phase change involved), its particles will begin to move faster which means that the temperature goes up.

What is thermal expansion?

As a substance is heated, particles begin to move faster and particles will move away from each other. This increases the volume of the substance and lowers its density.

Describe the three mechanisms of heat flow and the conditions under which they occur?

- Conduction - Objects are in contact with each other and energy is transferred through the collisions of particles - Convection - Occurs in a fluid (gas or liquid) where heated material will rise due to a drop in density. As it rises it will lose energy to its surroundings through conduction and its temperature will fall. This causes its density to drop so that it sinks again and can be heated by the energy source once again. - Radiation - Occurs when photons of light are transferred between objects. Radiation can occur across empty space (vacuum).

14) Describe the processes of melting, freezing, boiling, and condensation.

- Melting (solid to liquid) - absorb energy from surroundings to move particles out of crystal lattice and slightly apart - no change in temp during the process - Freezing (liquid to solid) - release energy to surroundings as particle move together and into crystal lattice positions - no change in temperature during the process. - Boiling (liquid to gas) - absorb energy from the surroundings to move particles far away from each other - no change in temperature during this process. - Condensation (gas to liquid) - release energy as particles that are far away from each move into close proximity to each other - no change in temperature during this process.

Describe the major characteristics of solids, liquids, and gases.

- Solids - Particles are closely packed and highly ordered. Solids hold their shape and volume. - Liquid - Particle are still closely spaced but are far more disordered. Liquids hold their volume but not their shape. - Gases - Particles are widely scattered and completely disordered. Gases take on the volume and shape of their container.

What do I have to do to the amount of heat absorbed in order to double the temperature change in an object?

Double the amount of heat absorbed.

Describe the potential energy changes that occur during phase changes.

During a phase changes the particles change position by getting farther apart or closer together but they do NOT change speed. Therefore there is no change in temperature during a phase change.

Describe the flow of heat when that really hot cup of coffee is placed on that really large iceberg.

Energy flows from the hot coffee to the ice berg. This causes the coffee to cool down and will melt a small portion of the ice berg.

Define thermal energy

Energy stored in the motions of the particles (molecules and atoms) of a substance

What is a convection current and how does it work?

Flows of a fluid caused by changes in density in a fluid as it is heated, rises, cools, and sinks again.

Describe the flow of heat in a system

Heat flows from region of high temperature to a region of low temperature until the two temperatures are equal.

How does heating and cooling affect the density of an object?

Heating lowers the density of a substance. Cooling increases the density of a substance

How does the thermal energy of a really hot cup of coffee compare to the thermal energy in a really large iceberg?

Ice berg likely has more thermal energy than the cup of coffee even though its temperature is lower. The particles are moving slower in the ice berg but there are far more of them that the in the cup of coffee.

If I need to heat up food quickly should I put a metal skillet on the burner or a glass skillet on the burner?

Metal is a better conductor than glass so it will transfer heat energy faster.

What is thermal equilibrium?

Occurs when the temperatures of two objects are equal so that no thermal energy can flow between them.

How does thermal energy compare to temperature?

Temperature is an average of the the kinetic energy of the particles of a substance while thermal energy is the total of the energy. Temperature does not depend upon the amount of the substance but the thermal energy does.

How does the temperature of a hot cup of coffee compare to a really large iceberg?

Temperature is higher which means that the particles are moving faster in the hot cup of coffee.

Why does a black can heat up faster than a white can when using radiant energy?

The black color absorbs all colors of light while the white can reflects most colors of light.