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

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

●

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

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)

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?