Heat and Temperature

1
Heat and Temperature

• Energy will flow from the object with the higher
  temperature to the object with the lower
  temperature.
• Heat is energy that flows between objects that
  have different temperatures.
• The SI unit of heat is the Joule.

2
Heat and Temperature

• FYI Cold cannot be measured. Cold is simply the
  absence of heat.

3
Heat and Temperature

• The thermometer is used to measure the presence
  or absence of heat.

4
Heat and Temperature

• Vocabulary
• Conduction
• Convection
• Radiation
• Conductor
• Insulator
• Specific Heat

5
Heat and Temperature

• Objectives
• Investigate and demonstrate how heat energy is
  transferred by conduction, convection, and
  radiation.
• Identify and distinguish between conductors and
  insulators.
• Explain how heat transfer is measured.

6
Heat and Temperature

• Objectives
• Calculate the amount of heat transferred between
  two objects.
• Calculate specific heat.

7
Heat and Temperature

• Recall that heat energy flows from substances of
  higher temperatures to substances of lower
  temperatures.
• There are three methods of heat energy transfer
• Conduction
• Convection
• Radiation

8
Heat and Temperature

• Heat energy is transferred by conduction when
  solid substances are in contact.
• Conduction is the transfer of heat throughout a
  substance.
• Some materials conduct heat better than others.

9
Heat and Temperature

• Heat energy is transferred through fluids by
  convection.
• Heat energy flows through a fluid in a pattern
  called a convection current.
• Convection currents form because heated fluids
  expand and become less dense than surrounding
  cooler fluids.

10
Heat and Temperature

• Radiation is the transfer of energy by infrared
  waves.
• Radiation can move energy over long distances.
• Unlike convection and conduction, radiation does
  not require matter to transfer energy.

11
Heat and Temperature

• Imagine eating a slice of apple pie directly from
  the oven.
• Which is hotter the apple filling or the crust?
• Why?

12
Heat and Temperature

• Substances differ in the way they absorb heat
  energy.
• The amount of heat required to raise the
  temperature of a substance by 1 K varies for
  different substances.
• Specific heat is the amount of heat required to
  raise the temperature 1 K for 1 kg of substance.

13
Heat and Temperature

• Specific heat is a physical property.
• Specific heat is represented by the letter c.
• Heat specific heat x mass x change in
  temperature
• H c x m x ?t

14
Heat and Temperature

• Sample
• How much heat is needed to raise the temperature
  of 0.5 kg of Al from 288 K to 293 K. The specific
  heat of Al is 897 J/kkg.

15
Heat and Temperature

• Vocabulary
• Melting Point
• Thermal Expansion