Physics Heat and Temp Test

A cold drink in a glass starts to chill your hand.

Conduction; your hand is in direct contact with the glass

The heat in your house needs to stay on in the winter because it slowly leaks outside through the windows and roof.

Second Law; the thermal energy is flowing from hot to cold

A person brings a cup of hot chocolate (70°C) into a room (20°C) and places a metal spoon (20°C) into the hot chocolate. Describe what happens to the temperatures of the hot chocolate, the spoon, and the air in the room after 10 minutes. Explain your answer. Identify and describe the primary method of heat energy transfer (conduction, convection, or radiation) between each of the following: the hot chocolate and the spoon the hot chocolate and the air in the entire room At what point will the net transfer of heat energy stop?

1. The three objects will eventually reach the same temperature. 2a. Hot chocolate and spoon is conduction because they're in direct contact. 2b. Hot chocolate and the air in the entire room is convection because the air is a fluid that is moving around and carrying the thermal energy 3. The net transfer of heat energy will stop when all of the objects reach thermal equilibrium.

Insulator

An object that prevents the movement of heat

Conductor

An object through which heat (or energy) can easily move

Warmer air from the ocean circulates towards the cooler land.

Convection; the air is a fluid that is moving around and carrying the thermal energy

When you rub your hands together, their kinetic energy turns into thermal energy.

First Law; the energy is being conserved and transforming into another type of energy

Name the seven EM waves from high energy to low energy (GXUVIMR)

Gamma, Xrays, Ultraviolet, Visible, Infrared, Microwave, Radio

Does heat rise or does hot air rise? Explain.

Heat does not rise; it always moves from hot to cold. Hot air does rise because it is less dense than cooler air and floats on top of it.

Temperature

How hot or cold an object is / how fast molecules are moving

If you have the six substances above, all the same mass, which will heat up the quickest and why?

Lead, because it has the lowest heat capacity so it will heat up and cool off faster.

Does a cup of hot water contain more heat than a cup of cold water? Explain.

No! Nothing can contain heat. Objects can only have a temperature

The sun heats up the pavement in a parking lot.

Radiation; the sun emits electromagnetic radiation that travels to the Earth

What is the relationship between the temperature of a substance and how fast the molecules move?

The faster the molecules move, the higher the temperature; they're directly proportional

What is absolute zero? At what temperature is it reached?

The lowest possible temperature when atomic motion stops; 0 Kelvins

Two spoons are outside on a cold winter day. One is made of metal, the other of wood. Which spoon feels colder, and is either spoon actually colder? Explain your reasoning.

The metal feels colder because its a conductor and moves heat away you're your hand faster. Neither are actually colder than the other because they're both in the same environment.

Heat

The movement of temperature

Which would be better - a 10 kg steel brick or a 10 kg jug of hot water at the same temperature? Explain.

The water jug would be better because it has a higher heat capacity and will stay warmer for a longer period of time

Molecules are never, truly, entirely motionless.

Third Law; nothing can reach absolute zero, so the molecules never really stop moving (they still have a little bit of kinetic energy)