Hot and Cold• Is there such a thing as ‘cold?’ For

example, does ice transfer ‘cold’ to a glass of Coca-cola to lower the temperature?– No. There is heat and lack of heat. Heat

energy from the Coca-cola is transferred to the ice which drops the temperature of the liquid and converts the ice to liquid water.

Temperature & Heat Energy

• TEMPERATURE: a measure of the average kinetic energy of the particles in an object (the degree of hotness).

– As average kinetic energy of an object increases, its temperature will increase.

– More average kinetic energy = higher temperature = hotter

– Less average kinetic energy = lower temperature = colder

• THERMOMETER: an instrument that measures and indicates temperature.

TEMPERATURE SCALES

• Fahrenheit and Celsius are common scales used for measuring temperatures.

• FAHRENHEIT SCALE: • Water freezes at 32ºF at SAP

• Water boils at 212ºF at SAP

• CELSIUS SCALE:• Water freezes at 0ºC at SAP

• Water boils at 100ºC at SAP

TEMPERATURE SCALES• The Kelvin scale is

based on absolute zero.

• Absolute zero is the temperature at which:

1. Molecular energy is at a minimum

and

2. Molecular motion stops

• It is 0 K on the Kelvin scale or –273.16ºC on the Celsius scale.

• Temperature changes indicate an energy transfer.

• HEAT: amount of energy transferred between objects that are at different temperatures.

• The transfer of energy as heat ALWAYS takes place from a substance at a higher temperature to a substance at a lower temperature.• For example, if you hold a glass of

ice water in your hands, energy will be transferred as heat from your hand to the glass.

Differences Between Heat and Temperature

• Compare:– one bucket of 30 °C water– one drop of 30 °C water

• Do they have the same temperature?– Yes, both have particles moving the same speed

• Do they have the same amount of heat?– No, the bucket has many more particles moving the

same speed, so MORE heat

• Temperature = the degree of hotness• Heat = the amount of hotness

THINK!

In your own words, define:

‘Temperature’=

‘Heat’=

Give one example of heat transferring from a high temperature substance to a low temperature substance.

• THERMAL CONDUCTION: the transfer of energy as heat through a material due to temperature differences.• Conduction involves heat moving through objects in direct contact or

through a single material.• Conduction takes place when two objects or parts of an object are at

unequal temperatures.

• CONVECTION: energy is carried away by a heated fluid that expands and rises above cooler, denser fluids.

• CONVECTION CURRENT: the vertical movement of fluids due to temperature variations.

• Convection results from the movement of warm fluids (gas or liquid).

• RADIATION: energy transferred as heat in the form of electromagnetic waves (infrared waves are heat).

• Unlike conduction and convection, radiation does not involve the movement of matter.

• Radiation is therefore the only method of energy transfer that can take place in a vacuum.

• Much of the energy we receive from the sun is transferred by radiation

• Black objects absorb solar radiation while white objects reflect solar radiation.

Exit Ticket #49-52

49. Temperature is a measure of the average ________ energy of an object’s particles.

A. kinetic

B. potential

C. mechanical

D. light

50. On the _______ temperature scale, water freezes at 0 degrees and

boils at 100 degrees.

A. Fahrenheit

B. Celsius

C. Kelvin

D. Kevin McCallister

51. As the kinetic energy of the molecules in a substance increases the ______

A. molecules move faster

B. molecules move at the same speed

C. molecules move slower

D. none of the above

52. The temperature at which all molecular motion stops is___ .

A. 0oF

B. 0 K

C. 0oC

D. 98oF

THNK!

Give an example of:

Conduction=

Convection=

Radiation=

• CONDUCTOR: Any material through which energy can be easily transferred as heat

• INSULATOR: Any material through which energy is difficult to be transferred as heat.

• Gases are extremely poor conductors.

• Liquids are also poor conductors.

• Some solids, such as rubber and wood, are poor conductors.

• Most metals are good conductors.

THINK!

What is it mean if something is a good conductor? Give an example.

What does it mean if something is a good insulator? Give an example.

• SPECIFIC HEAT: describes how much energy is required to raise an object’s temperature.

– Specific heat is defined as the quantity of heat required to raise a certain amount of mass of a material 1 K or 1°C.

Specific Heat Equation

energy = (specific heat) x (mass) x (temperature change)

energy = c * m * t

Specific Heat Practice• When trying to boil water, which heats up faster – the metal pot or

the water?– Metal pot!– Water has HIGH specific heat (4.186)

• Takes MORE heat to cause the temperature to rise

– Stainless Steel has LOW specific heat (0.500) • Takes LESS heat to cause the temperature to rise

• When at the beach on a sunny day, which is hotter – sand or water?– Sand!– Water has HIGH specific heat (4.186)– Sand has LOW specific heat (0.835)

THINK!

Water has a very high specific heat. Give one reason why this helps us stay alive.

Exit Ticket: Heat Transfer

#53-56

53. The type of energy transfer that takes place between objects in contact is

a.Conduction

b.Convection

c.Contraction

d.Radiation

54. Which of the following would be an example of a good conductor of heat energy?

A.Liquid

B.Wood

C.Air

D.metal

55. The type of energy transfer that does not involve the movement of matter (most of the energy from the sun is an example of this)

a.Conduction

b.Convection

c.Insulation

d.Radiation

56. What form of heat transfer is represented by this illustration?

A. conduction

B. convection

C. Insulation

D. radiation

Understanding Concepts1. What happens to the energy that is lost when

an engine is less than 100% efficient?

A. It is destroyed during combustion.B. It is converted to heat and transferred to the environment.C. It is converted to matter in the form of gases that enter the atmosphere.D. It is lost as friction between the tires of the vehicle and the surface of the road.

Chapter 13

Understanding Concepts1. What happens to the energy that is lost when

an engine is less than 100% efficient?

A. It is destroyed during combustion.B. It is converted to heat and transferred to the environment.C. It is converted to matter in the form of gases that enter the atmosphere.D. It is lost as friction between the tires of the vehicle and the surface of the road.

Chapter 13

Understanding Concepts2. What change occurs in matter when its

temperature is increased?

F. The specific heat of the material increases.G. Atoms and molecules in the material move faster.H. The attraction between atoms and molecules increases.I. The frequency of collisions between atoms and molecules decreases.

Chapter 13

Understanding Concepts2. What change occurs in matter when its

temperature is increased?

F. The specific heat of the material increases.G. Atoms and molecules in the material move faster.H. The attraction between atoms and molecules increases.I. The frequency of collisions between atoms and molecules decreases.

Chapter 13

Understanding Concepts

3. What transfer method carries energy from the sun to Earth?

A. conduction

B. convection

C. insulation

D. radiation

Chapter 13

Understanding Concepts

3. What transfer method carries energy from the sun to Earth?

A. conduction

B. convection

C. insulation

D. radiation

Chapter 13

Understanding Concepts

4. Why does the temperature of hot chocolate decrease faster if you place a metal spoon in the liquid?

Chapter 13

Understanding Concepts

4. Why does the temperature of hot chocolate decrease faster if you place a metal spoon in the liquid?

Answer: Metal is a good conductor of heat, so energy is transferred rapidly to the metal and from the metal to the air.

Chapter 13

Understanding Concepts

5. Determine why you can’t cool your kitchen on a hot day by opening the refrigerator to let the cold air escape into the room.

Chapter 13

Understanding Concepts

5. Determine why you can’t cool your kitchen on a hot day by opening the refrigerator to let the cold air escape into the room.

Answer: The cooling system releases more heat into the room than it removes from the interior of the refrigerator.

Chapter 13

Reading Skills

6. How does the specific heat of water affect its ability to moderate coastal temperatures?

The specific heat of water is very high compared to that of the soil and rock that make up land surfaces. In areas near a large body of water, the water does not heat as quickly as the land during the summer and does not cool as quickly as the land during the winter. This causes the climate in coastal areas to be generally milder than inland areas at the same latitude. For example, San Francisco has cooler summers and warmer winters than Sacramento, less than 150 km to the east.

Reading SkillsThe specific heat of water is very high compared to that of the soil and rock that make up land surfaces. In areas near a large body of water, the water does not heat as quickly as the land during the summer and does not cool as quickly as the land during the winter. This causes the climate in coastal areas to be generally milder than inland areas at the same latitude. For example, San Francisco has cooler summers and warmer winters than Sacramento, less than 150 km to the east.

6. How does the specific heat of water affect its ability to moderate coastal temperatures?

Answer: The high specific heat means that water can store heat during warm months and release it when the land and air are cooler in winter.

Interpreting Graphics

7. What form of heat transfer is represented by this illustration?

F. conduction

G. convection

H. insulation

I. radiation

Interpreting Graphics

7. What form of heat transfer is represented by this illustration?

F. conduction

G. convection

H. insulation

I. radiation