Heat & Thermal Energy

Chapter 11 Heat & Thermal Energy

11.1 Heat and Thermal Energy

●To change the temperature you need to add or subtract energy

●When you add heat the temperature and energy go up

Heat, temperature, and Thermal energy

●HEAT is the transfer of energy from 1 object to another

●We call this flow of thermal energy heat

11.1 Heat and Thermal Energy

●Heat is really just another word for thermal energy that is moving

●Heat flows any time there is a difference in temperature

●Heat flows naturally from the warmer object (higher energy) to the cooler one (lower
energy)

●In the case of the melting chocolate bar, the thermal energy lost by your hand is equal
to the thermal energy gained by the chocolate bar

Multiple Choice

What property of an object is related to the average kinetic energy of the particles in that object?

• specific heat

• mass

• conducitvity

• temperature

Multiple Choice

As the temperature of an object rises, so does the

• kinetic energy of the object.

• mass of the object.

• thermal energy of the object.

• potential energy of the object.

Multiple Choice

Which quantity has the unit ^oC (degrees Celsius)

• Thermal Energy

• Heat

• Temperature

• Kinetic Energy

Multiple Choice

When heat is absorbed by an object, the speed of the particles in the object IS UNCHANGED.

• True
• False

11.1 Heat and Thermal Energy

●Heat and temperature are related, but they are not the
same thing

●Thermal Energy is the TOTAL ENERGY of an
Object and depends on the size of the Object

T

THERMAL ENERGY

SIZE MATTERS
With 2 objects at the
Same temperature, the
LARGER object has
Total (THERMAL)
energy

11.1 Heat and Thermal Energy

Units of heat and thermal energy

●The metric unit for measuring heat is the joule

●This is the same unit used to measure all forms of energy, not just heat

●One calorie is the amount of energy (heat) needed to increase the
temperature of 1 gram of water by 1 degree Celsius

●

Multiple Choice

How is "Thermal energy" defined?

• Measure of the average kinetic energy of the molecules in an object

• The process by which an object gains thermal energy

• Transfer of thermal energy

• Total kinetic and potential energy of the molecules in an object

Multiple Choice

Thermal expansion occurs when particles of matter move farther apart as temperature increase.

• True

• False

Multiple Choice

Object A is much larger than Object B, but both are made of the same material.  If both objects are at the same temperature, the thermal energy of Object A is GREATER the thermal energy of Object B.

• True
• False

Multiple Choice

There are four cups of hot cocoa. The cup sizes are shown. The temperature of the cocoa in each cup is 25 degrees celsius. Which cup has the MOST thermal energy?

• Large cup (Trenta)
• Small cup (Tall)
• Venti
• All three are the same temperature so they have same thermal energy

Calories

●The unit used for measuring the energy content of the food we eat is the kilocalorie, which equals
1,000 calories

●The kilocalorie is often written as Calorie (with a capital C)

●If a candy bar contains 210 Calories, it contains 210,000 calories, or 879,060
joules!

11.1 Heat and Thermal Energy

●Another unit used for heat energy is the British thermal unit, or Btu

●It is used for measuring the heat produced by heating systems or heat removed by air-conditioning systems

●A Btu is the quantity of heat it takes to increase the temperature of 1 pound of water by 1 degree Fahrenheit

11.1 Heat and Thermal Energy

Specific heat

●DIfferent materials HEAT UP or COOL DOWN at different RATES

●It depends in part on the mass of the object

●The rate at which materials HEAT UP or COOL DOWN is called a materials SPECIFIC
HEAT

11.1 Heat and Thermal Energy

●You need to add 4,184 joules of heat to one kilogram of water to raise the temperature by 1℃

●You only need to add 470 joules to raise the temperature of one kilogram of steel by 1℃

●IT takes 9 MORE times the energy

●WATER HAS A HIGHER SPECIFIC HEAT than STEEL

11.1 Heat and Thermal Energy

Specific heat

●How much heat (energy) is needed to raise the
temperature of one kilogram of a type of matter by one
degree Celsius

●Specific heat is measured in joules per kilogram per
degree Celsius (J/kg℃)

●A large specific heat means you have to put a lot of energy
for each degree of increase in temperature

Specific Heat

11.1 Heat and Thermal Energy

Why is specific heat different for different materials

●Materials made up of heavy particles (atoms or molecules) have low specific heat compared with
materials made up of lighter ones

●Energy that is divided between fewer particles means more energy is gained per particle, and therefore more temperature change that is faster

Multiple Choice

The amount of heat needed to raise the temperature of one gram of a material by one degree Celsius is called

• Specific Temperature.

• Specific Heat

• Absolute Heat

Multiple Choice

A high specific heat means...

• It heats up quickly with energy added
• It requires more energy to change temperature

Multiple Choice

Specific heat is....

• The measure of kinetic energy of an objects particles
• A measure of the energy needed to increase the average kinetic energy of the particles
• The heating caused by the motion of flluid due to temperature difference
• The transfer of energy by electromagnetic radiation

Multiple Choice

The lower a material's specific heat, the more its temperature rises when a given amount of energy is absorbed by a given mass.

• True

• False

11.1 Heat and Thermal Energy

Calculating energy changes from heat

●How could you figure out how much energy it would take to
heat a swimming pool or boil a pot of water?

●The heat equation below tells you how much energy (E) it
takes to change the temperature (T) of a mass (m) of a substance with a specific heat value (C)

Multiple Choice

What is the symbol for Specific Heat

• Q
• t
• m
• C

Multiple Choice

Copper, Stainless Steel, Carbon Steel, and Zinc were all heated using the same thermal energy.  What material would be the coolest after being heated?

• Copper
• Carbon Steel
• Zinc
• Stainless Steel

Multiple Choice

Which of the following containers of sand has atoms/molecules with the greatest average kinetic energy?  

• 1 kg at 20^oC
• 2 kg at 20^oC
• 4 kg at 20^oC
• None has a greater amount because all have the same average kinetic energy

Key Topics HEAT

1)

Compare & contrast Heat, Temperature & Thermal Energy

2)

Describe the heat transfer that occurs when warm soda in placed in a cooler full of ice.

3)

Compare & contrast a Calorie & a BTU

4)

What is Specific Heat?

5)

What does a HIGH # and a LOW # indicate?

6)

What is the energy necessary to change the temperature of a swimming pool containing 158,000 Kg of water from 65 degrees to 80 degrees Celsius?

7)

How much energy is required to change the temperature 10,000 Kg of steel
from 60 degrees C to 95 degrees C?