Task No. 6 Heat Transfer PDF

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Summary

heat transfer...

Description

Scientist

HEAT TRANSFER

Date

Key Concepts

• How is temperature measured? • How is heat transferred in the troposphere? All substances are made up of small particles, which can be atoms or molecules, that are constantly moving. The faster the molecules are moving, the more energy they have. The total energy of motion in the particles of a substance is called thermal energy. Temperature is the average amount of energy of motion in each particle of a substance. It is a measure of how hot or cold a substance is. Temperature is one of the most important elements of weather. Air temperature is usually measured with a thermometer. A thermometer is a thin glass tube with a bulb on one end that contains a liquid, usually mercury or colored alcohol. Thermometers work because liquids expand when they are heated and contract when they are cooled. Temperature is measured in units called degrees. Oh the Celsius scale, the freezing point of pure water is 0°C and the boiling point of pure water is 100°C. On the Fahrenheit scale, the freezing point of water is 32°F and the boiling point is 212°F. Heat refers to the energy transferred from a hotter object to a cooler one. Heat is transferred in three ways: radiation, conduction, and convection. Radiation is the direct transfer of energy. The direct transfer of heat from one substance to another substance that it is touching is called conduction. Conduction works well in some solids, but not as well in fluids (liquids and gases). In fluids, molecules can move from place to place and take their heat with them. The transfer of heat by the movement of a fluid is called convection. Radiation, conduction, and convection work together to heat the troposphere. Air near Earth's surface is warmed by conduction of heat from the surface to the air. Within the troposphere, heat is transferred mostly by convection. When the air near the ground is heated, the molecules have more energy and move faster. The molecules bump into one another and move farther apart, or become less dense. Cooler, denser air sinks, forcing the warmer, less dense air to rise. The upward movement of warm air and the downward movement of cool air form convection currents. Convection currents move heat throughout the troposphere.

© Ruthe Hall The Science

Understanding Main Ideas Label each picture with the type of heat transfer that it shows.

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3.

2.

4.

Answer the following questions in the spaces provided. 5. How is air temperature usually measured? 6. At what temperature on the Celsius scale does pure water freeze? At what temperature does it boil? 7. Name the three -ways by which heat is transferred. 8. How is heat transferred from the sun to Earth? 9. Heat is moved through the troposphere mainly by

Building Vocabulary Fill in the blank to complete each statement.

10.

The total energy of motion in the particles of a substance is called .

11.

is the average amount of energy of motion in the particles of a substance.

12. A(n) is a thin glass tube with a bulb on one end that contains a liquid, usually mercury or colored alcohol13. The energy transferred from a hotter object to a cooler one is referred to as . 14. The direct transfer of heat from one substance to another substance that it is touching is called . 15. The transfer of heat by the movement of a liquid is called

© Ruthe Hall The Science

Using words from the word boxes below, complete the paragraph about heat transfer. faster conductio n warmer

matter

less convectio n transfer

radiation

contact

cold

All

hot more

has heat. Heat is a form of . The

solid energ y absor b vibrat e

fluid emit temperatu re waves

caused by particles in an object that

the particles of an object vibrate, the

the

object will be. Because particles of an object are always moving, heat

is

always happening. Heat always flows in the same direction: from

to

Heat transfer will stop once two objects reach the same

. This is

.

known as equilibrium. There are three key ways that heat transfers. With objects come into direct

objects, heat transfers when the

with other things. This is known as

. Liquids and gases

are different. Because these two states of matter flow, or are , heat transfer happens when warmer, dense particles rise and cooler, dense particles sink. This ongoing process is known as a

current. Heat can also be transferred

through space (distance) in the form of . This process is known as

. All objects give off, or

heat. All objects also take in, or

, some

, heat.

Identify the method of heat transfer that takes place in each illustration. Write the method of heat transfer underneath the picture.

1.

2.

3.

4.

5.

6.

© Ruthe Hall The Science

In the boxes below, draw an example of each type of heat transfer. Explain how heat is being transferred in your example. Conduction

Explanation:

Convection

Explanation:

Radiati on

Explanation:

In each of the following situations, identify the method of heat transfer taking place. Write conduction, convection, or radiation on the line next to the statements. Choose the best answer. 1. You are stirring a bowl of hot soup with a metal spoon. The spoon starts to feel warmer because of . 2. You buy a lava lamp from the store. As the lamp heats up, blobs of liquid rise to the top then sink back down to the bottom. This process continues because of . 3. You are doing your homework at a desk that is underneath a lamp. You start to feel hotter because of from the lamp. 4. Your best friend has a bunk bed. You move from the bottom bunk to the top bunk and notice that the air is warmer. The warm air rises because of . 5. You are in science class and want to see if the hot plates were used recently. You place your hand over the hot plate. Without touching the hot plate, your hand feels warmer. Heat is transferred to your hand by .

6. You are roasting marshmallows at a campfire. The metal skewer (stick) that you’re cooking your marshmallow on burns your hand because of .

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