1. 13.2
Transferring Thermal Energy
Transfer of Energy
Conduction-transfer of energy by direct contact.
Faster moving particles of one substance come into contact with slower moving molecules of another substance.

2. Conduction can take place in solids, liquids, & gases.
It is more likely to take place in solids
Metals are especially good conductors.
Convection-transfer of energy in a fluid by the movement of the heated particles.
Any material that can flow is considered a fluid.
2. Heated particles collide with each other and transfer their energy.
3. As particles move faster, they tend to be farther apart.

3. Offshore convection currents
Convection currents form by fluids heating up, rising, cooling off, falling.

4. Radiation-the transfer of energy by electromagnetic waves.

6. Insulators- materials that slows heat flow.
Metals are typically poor insulators.
2. Gases are very good insulators.
3. Some types of insulators use pockets of air to help keep heat from flowing.

7. Specific Heat
Specific Heat-the amount of heat that is needed to raise the temp. of 1kg of some material by 1°C (or 1K).
Specific heat is measured in J/kg·K OR J/g·ºC
Table 1 pg. 432
Water is a good coolant because it has a high specific heat.

8. Grams(g) OR kilograms(kg)
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the water’s temperature from 250C to 370C?
Symbol
Meaning
Unit Q
Energy
Joules (J) Dt
change in temperature ºC m
mass
Grams(g) OR kilograms(kg) c
specific heat
J/kg.K OR J/g·ºC

9. Grams(g) OR kilograms(kg)
Specific Heat Problem 2
Identify an unknown substance with a mass of kg that absorbs 6.33 x 103J, in which a temperature change of 15.50C is observed?
Symbol
Meaning
Unit Q
Energy
Joules (J) Dt
change in temperature ºC m
mass
Grams(g) OR kilograms(kg) c
specific heat
J/kg.K OR J/g.ºC

10. Practice: Pg. 434 – Questions 1 – 6