7.Science.U02.L3-5.Heat Transfer

Heat Transfer

Multiple Choice

Which of the following statements are true of alkali metals?

• They react explosively with water.

• They don't react with any other elements.

• They become more soluble as the solve gets colder.

• They are poisonous.

Multiple Choice

If Carbon Dioxide is dissolved into soda, what is the solute?

• Carbon Dioxide

• Soda

Multiple Choice

If Carbon Dioxide is dissolved into sod, what is the solvent?

• Carbon Dioxide

• Soda

Multiple Choice

If Carbon Dioxide is dissolved into soda, is this a physical or chemical change?

• Physical Change

• Chemical Change

There are 3 types of Heat Transfer:

• Conduction

• Convection

• Radiation

Heat Transfer

We know from our chemistry unit that the particles within all matter are always moving. The speed of the molecules depends on how hot the substances is. In other words, heat is energy from the motion of particles. Heat passes from hotter to objects to colder objects, or hotter areas to colder areas. Temperature is a measure of the average speed of the molecules in a substance.

Conduction

Conduction is the transfer of heat between two objects that are touching. The heat moves from one molecule to another. As one molecule is heated it begins to move rapidly. As it does so, it bumps into the molecules around it, making them move faster and passing on some of its heat energy. Through this process all the molecules of an object pass heat from one to another until they are all hot.

Conductors

Objects that are good at conducting heat are called conductors and are made out of metals. Objects that are not good at conducting heat are called insulators and they are made of non-metals

• Heat is energy from the motion of particles. It passes from hot to cold.

• Conduction is the transfer of heat between objets or particles that are touching. Fast moving molecules bump into other molecules and make them move faster.

• Conductors - allow heat to pass.

• Insulators - stop heat from passing.

Multiple Choice

In conduction, heat is passed between two materials that are______.

• Liquids

• Plugged in

• Touching

• Giving off light

Multiple Choice

Which of the following quotes would be the best evidence to support the statement that "wooden objects are good insulators of heat?"

• "Conduction is the transfer of heat between two objects that are touching."

• "Heat passes from hotter objects to colder objects, or hotter areas to colder ares."

• "As the hot dog cooks, the fire heats the end of the hanger."

• "Though the stick may have caught fire, it would not have conducted the heat to your hand."

Multiple Choice

What is conduction?

• Heat transfer from a liquid to a gas.

• Heat transfer between objects that are touching.

• A specific type of heat.

• Heat transfer between solid objects.

Multiple Choice

Which state of matter has particles that cannot change their place?

• Solids

• Liquids

• Gases

Multiple Choice

What type of heat transfer takes place when you touch a warm mug of hot chocolate?

• Radiation

• Conduction

• Convection

• None of the above.

Multiple Choice

Conduction Requires

• Electricity

• Air or water flow

• The electromagnetic spectrum and particles

• direct contact.

Convection

Convection is the transfer of heat through fluids (liquids and gases) in a circular pattern. When a fluid gets hot the molecules begin to move faster which spreads them farther apart so they become less dense and rise. When a fluid cools the molecules begin to slow down and move closer together due to attraction which makes the fluid more dense so it sinks.

Multiple Choice

Heat transfer always moves...

• cold to hot

• hot to cold

• east to west

• north to south

Multiple Choice

If you walk barefoot on hot asphalt, energy is transferred by which process?

• Convection

• Conduction

• Radiation

• Reflection

Multiple Choice

When air is heated, what happens to its density?

• increases

• decreases

• remains the same

Multiple Choice

Convection can take place in____________.

• Solids only

• liquids and gases only

• liquids only

• solids, liquids, and gases

Multiple Choice

Energy is transferred as heat between two objects of ___________ temperatures.

• Differing

• Same

Multiple Choice

The diagram shows a refrigerator. The cooling unit is placed at the top. The cooling unit cools the air near it. What happens to the density of the air as it cools, and how does it move?

• The density of air increases. It moves down.

• The density of air decreases. It moves down.

• The density of air increases. it moves up.

• The density of air increases. It moves up.

Multiple Choice

Which of the following is an application of convection?

• The movement of heat through a metal pan to the food.

• The sea breeze that blows from sea to land.

• The use of an ice box to keep drinks cool.

• The use of wool blanket to keep the body warm.

Multiple Choice

In the process of convection, energy is transferred _________.

• because of temperature differences in a solid.

• by the diffusion of molecules throughout a fluid.

• because of density difference in a liquid.

• by the vibration of molecules.

Multiple Choice

Which of the following correctly shows the direction of convection currents in water?

Directions: click the image to the left to make it bigger.

• A

• B

• C

• D

Multiple Choice

Which of the following is an example of conduction?

• Warm air flowing up from a subway vent.

• A scarf sitting on a radiator and getting warm.

• The heat radiating out from a light bulb.

• Feeling the warmth of the sun on your face.

Multiple Choice

Which of these would have the highest density?

• Feathers

• An iron bar

• A jacket

• A bottle of water

Multiple Choice

Which of these would have the lowest density?

• Hot water

• Cold water

• Hot air

• Cold air

Multiple Choice

Which state of matter does NOT undergo convection?

• Solid

• Liquid

• Gas

Radiation

Radiation is the transmission of heat through electromagnetic (light) waves. These waves can travel through empty space as well as through matter (imagine light passing through a window). Electromagnetic waves are NOT a type of matter. When you feel the light of the sun on your face, or the heat of a light bulb, that is radiation.

Heat Transfer

Multiple Choice

The earth receives heat energy from the sun by ____________, which is the transfer of energy as electromagnetic waves?

• Radiation

• Conduction

• Convection

• Greenhouse effect.

Multiple Choice

Which of the following statements describes the molecules of a substance that are getting warmer?

• The molecules move slower.

• The molecules get closer together.

• The molecules stop moving.

• The molecules move faster.

Multiple Choice

The handle of a pan gets hot while the pan is on the burner. This is an example of___________.

• Conduction

• Convection

• Radiation

Multiple Choice

Warm air rises off of asphalt on a summer day. This is an example of ______________.

• Conduction

• Convection.

• Radiation.

Multiple Choice

Cool air sinks at night, causing breezes. This is an example of _____________.

• Conduction

• Convection

• Radiation.

Multiple Choice

A lizard sits on a warm rock to absorb its heat. This is an examples of _____________.

• Conduction

• Convection

• Radiation.

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: Your hand touches the burner on the stove.

• Conduction

• Convection

• Radiation.

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: You feel the warmth of the sun on a warm summer day.

• Radiation

• Conduction

• Convection

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: Magma (melted rock) heats up and rises, then cools and sinks.

• Radiation

• Conduction

• Convection.

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: You turn on the heater in your house, and you begin to feel warmer.

• Radiation

• Conduction

• Convection.

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: You accidentally touch the hot part of an iron.

• Radiation

• Conduction

• Convection

Multiple Choice

Directions: State if the situation is example of radiation, conduction, or convection.

Situation: Hot soup moves to the top of the pot and cool soup sinks to the bottom.

• Radiation

• Convection

• Conduction.

Multiple Choice

What is the definition of CONDUCTION?

• When heat is transferred from objects like rays of light or electromagnetically.

• When heat transfers from objects that are touching.

• a hot liquid or air that expands, becomes less dense, and rises or becomes more dense, and sinks.

• When heat transfers through the heater or AC in your house.

Multiple Choice

What is the definition CONVECTION.

• When heat transfers through waves.

• A hot liquid or air that expands, becomes less dense, and rises or becomes more dense, and sinks.

• When heat transfers from objects that are touching.

• Heat traveling from the sun.

Multiple Choice

Baby chickens are kept warm from heat lamps, this demonstrates what type of heat transfer?

• Conduction

• Radiation

• Convection

Multiple Choice

Walking on the warm sand with your bare feet demonstrates this type of heat transfer.

• Conduction

• Radiation

• Convection.

Multiple Choice

Near the ceiling of a room the air is warmer. The warm air rises because of

• Conduction

• Radiation

• Convection.

Multiple Choice

What is something that prevents heat, electricity, sound, light...to pass through it?

• Insulator

• heat transfer

• conduction

• conductor

Multiple Choice

What is something that readily conducts heat, electricity, sound...

• insulator

• thermal equilibrium

• conduction

• conductor

Multiple Choice

The transfer of heat in a fluid (gas or liquid) by means of up & down movements called convection currents.

• Conduction

• Radiation

• Convection.

Multiple Choice

The transfer of heat through a vacuum (empty space).

• Conduction

• Radiation

• Convection

Multiple Choice

The transfer of heat through a medium (material) by direct contact of molecules.

• Conduction

• Radiation

• Convection.