1. Quick recap...

2. Heat, Temperature and Internal energy Define: 1. Heat Defined as the transfer of energy across a boundary due to a temperature difference. 2. Temperature A measure of how hot or cold something is. Defined from the average kinetic energy of atoms and molecules. 3. Internal energy Defined as the energy (kinetic and potential) associated with the random, disordered motion of atoms molecules.

3. Objects A (metal) and B (plastic) are two at the same temperature and have the same mass. If 100J of internal energy is removed from each object (A and B), will they be at the same temperature? AB

4. No, because they will have a different specific heat capacities. Metal has a lower specific heat value which makes it more sensitive to heat transfer.

5. So which object will have the higher temperature? B Plastic

6. How did this happen?

7. Thermal expansion As the temperature of a liquid or solid increases, the molecules vibrate faster and occupy more space. This results in a volume increase known as thermal expansion, thus the rails bent.

8. Accommodating thermal expansion

9. Equations Equation for energy associated with temperature change of an object? Equation for energy associated with phase change?

10. Equations Equation for energy associated with temperature change of an object? Q = mc∆T Equation for energy associated with phase change? Q = mL

11. Equations From Q = mL, there are 2 different L values can that be used. 1. L f = Latent heat of fusion (solid-liquid, liquid-solid) 2. L v = Latent heat of vapourisation (liquid-gas, gas-liquid)

12. Heat transfer For each case, how does heat get transferred? 1. Table to hand 2. Saucepan to egg in boiling water 3. Sun to Earth

13. Heat transfer For each case, how does heat get transferred? 1. Table to hand: Conduction, direct contact 2. Saucepan to egg in boiling water: Convection, convection currents circulating in water 3. Sun to Earth: Radiation, no medium in space