HEATING AND COOLING PHYSICS 2 AB Mr D

HEATING AND COOLING PHYSICS 2 AB Mr. D. Patterson 2012

Outcomes Describe and explain the term specific heat capacity Describe and explain how specific heat capacity affects changes in temperature

Specific Heat Capacity The amount of energy required to increase the temperature of an object is proportional to the mass

Specific Heat Capacity More energy is required to have a larger increase in temperature

Specific Heat capacity The amount of energy required to increase the temperature depends on the material of the object Heat capacity is the term used for the amount of energy required to raise the temperature of an object

Specific Heat Capacity Definition of specific heat capacity: Amount of energy required to change the temperature of one kilogram of a material by 1 K (or 1 degree C). Formula of specific heat capacity:

Specific Heat Capacity c = specific heat capacity (J/kg. K) Q = heat energy (J) m = mass (kg) T = temperature (K or degree C)

Specific Heat Capacity Example Hot water tank contains 135 litres of water. It starts out at 293 K. Specific heat capacity of water is 4200 J/kg. K How much energy is needed to raise the temperature to 343 K? Solution = 28. 3 MJ

Thermal equilibrium Most problems involve heat energy transferring from one object to another.

Thermal Equilibrium In a closed system, all objects will end up having the same temperature. The amount of heat lost must be the same as the amount of heat gained (conservation of energy)

Example problem A 20 g lead nut at a temperature of 80 deg C is placed in a polysterine cup holding 250 ml of water at a temperature of 22 deg C. What is the final temperature of the water? Ignore any heat loss to the cup or surroundings Solution = 22. 14 deg C