Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. What equation is used to calculate change in thermal energy?
   • The amount of Energy stored in or released from a system as its temperature changes can be calculated using the equation: change in thermal Energy = mass x specific heat capacity x temperature change
2. How much energy is needed to increase the temperature of 500 g of lead from 20oC to 45oC? The specific heat capacity of lead is 128 J/kg oC.
   • mass of lead = 500 x 1000 = 0.5 kg temperature change = 45 x 20 = 25oC Energy needed = 0.5 x 128 x 25 = 1600 J (1.6 kJ)
3. What is meant by the term 'specific heat capacity'?
   • The specific heat capacity of a substance is the amount of Energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
4. What is meant by the term 'power'?
   • Power is defined as the rate at which Energy is transferred or the rate at which work is done.
5. How is the rate of a cooling building affected by the thickness and the thermal conductivity of it's walls?
   • The higher the thermal conductivity of a material, the higher the rate of Energy transfer by conduction across the material. The higher the thickness of the walls, the slower the cooling effect of a building.
6. What definition is illustrated in the following example: comparing two electric motors that both lift the same weight through the same height but one does it faster than the other?
   • The definition illustrated by the following example is power: comparing two electric motors that both lift the same weight through the same height but one does it faster than the other.
7. What affect does a higher thermal conductivity have?on the rate of energy transfer?
   • The higher the thermal conductivity of a material the higher the rate of Energy transfer by conduction across the material