Heat Flows

Heat Transfer

Heat flows from HOT to COLD. The bigger the temperature difference, the more heat moves.

BUT the heat needs a ride--either conduction through a solid (or unmoving fluid), convection through a moving gas or liquid, or radiation using visible or invisible light.

Multiple Choice

In heat transfer, heat always flows from the _______________ substance to the _______________ substance.

• hotter to colder

• colder to hotter

• hotter to hotter

• colder to colder

Conduction

• Heat transferred in a solid or between two things that are touching.

• Good conductors like METAL move a lot of heat quickly, like a cooking pot or a cold lamp post.

• Things that DON'T transfer heat quickly are called insulators. It can be hot on one side of an insulator and cold on the other side without too much heat transferring.

• Your coat is a good example of an insulator.

Convection

• Moving Air, or another liquid or gas can move lots of heat with it.

• A fan or pump can FORCE convection

• But warm air rises, so even with no fan, air will move given the chance.

• Cold air sinks--thats why those open freezers at the grocery store do OK with no lid.

Radiation

• EVERYTHING is glowing

• Humans emit Infrared light

• Hotter things (600 c) glow red and radiate more

• 900 c things glow orange, and radiate a ton.

• 1200 c things glow WHITE

• Past that you start to get more UV light.

Multiple Choice

What is a conductor?

• a material that heat moves through easily

• a material that heat does not move through easily

• a material that turns cold when heated

• a tool for measuring temperature

Multiple Choice

Which of the following is not a form of heat transfer?

• Convection

• Conduction

• Insulation

• Radiation

Multiple Select

Which of the following are examples of heat transfer through conduction? You may choose more than one.

• Using hand warmers to warm up your hands

• Hot air balloon rising

• Burning your hand on a curling iron

• Spoon getting hot while sitting in hot tea

Multiple Select

Which of the following are examples of heat transfer through convection?

You may choose more than one.

• Hot air balloon rising

• The second floor of a house is warmer than the first floor

• Boiling water on the stove

• Sitting around a campfire and feeling the heat from the flames

Multiple Select

Which of the following are examples of heat transfer through radiation? You may choose more than one.

• Feeling the heat from a candle

• The water at the top of the pool feels warmer than the deep end

• The sun warming the Earth

• A space heater warming the room

Fill in the Blanks

Convection, conduction or radiation?

Smoke rising in a room due to a fire

Fill in the Blanks

Convection, conduction or radiation?

Chocolate melting in your hand

Fill in the Blanks

Convection, conduction or radiation?

A hot air balloon rising in the sky

Fill in the Blanks

Convection, conduction or radiation?

The heat a snake feels from the lamp above him

Fill in the Blanks

Convection, conduction or radiation?

The reason heating vents are usually placed in the floor of homes in the North.

Fill in the Blanks

Convection, conduction or radiation?

The reason you use an oven mitt to get a cookie sheet out of the oven.

Fill in the Blanks

Convection, conduction or radiation?

Heat from a blow dryer

Fill in the Blanks

Convection, conduction or radiation?

Heat you feel from an electric blanket

Multiple Choice

Which is an example of heat being transferred by conduction?

• a furnace blowing hot air through vents

• an ice cube melting in a person’s hand

• boiling water transferring heat to noodles

• the sun heating water in a swimming pool

Multiple Choice

Which direction will the heat flow while this person holds a hot cup of tea?

• from the cup to her hand
• from her hand to the cup
• no heat is transferred

Multiple Choice

If I want two things to stay different temperatures from each other, I need to:

• Maximize heat Transfer

• Minimize heat transfer

• Make them touch a lot

• Blow on both with a fan

Multiple Choice

Hot water rises and cold water sinks. Is this:

• Convection

• Conduction

• Radiation

Multiple Choice

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

• conduction

• convection

• radiation

Multiple Choice

Which best describes the process of convection?

• Convection is the primary way  heat travels  through rays.
• Convection is the primary way heat travels  through metals.
• Convection is the primary way heat travels  through appliances.
• Convection is the primary way heat travels  through liquids and gasses.

Multiple Choice

Cold Pack on Person

• Heat is transferred from the cold pack to the person.

• Heat is transferred from the person to the cold pack

• The cold pack is getting colder. The person is getting warmer.

Multiple Choice

When I emit (send out) IR radiation, my body gets:

• Hotter

• Cooler

• Stays the Same

• Humans don't emit radiation

Multiple Choice

The baby chickens kept warm by the heat lamps. This is an example of ________.

• conduction

• convection

• radiation

Multiple Choice

The heat transferred from the Sun to the Earth by waves is called ________.

• conduction

• radiation

• convection