Thursday, 4 September 2014

HEAT ENERGY AND SPECIFIC HEAT CAPACITY


HEAT ENERGY AND SPECIFIC HEAT CAPACITY
Data:
Specific heat capacities:  
Water 4200 J/kgoC               Copper 400 J/kgoC              Aluminium 900 J/kgoC   Concrete  3300 J/kgoC            Lead 126 J/kgoC

1. Should saucepans be made of material with a high or low specific heat capacity? Explain your answer.

2. How much heat energy is needed to raise the temperature of a 200 g piece of lead by 250 oC?

3. A 150 g potato cools from 100 oC to 50 oC. If the specific heat capacity of potato is 2000 J/kgoC how much heat does the potato loose?

4. A 300 g copper saucepan contains 1 kg of water. If the water and the saucepan are heated from 20 oC to 100 oC calculate:

(a) how much heat energy the water gains
(b) how much heat energy the saucepan gains

5. A small piece of aluminium of mass 50 g is used on a circuit that has a normal temperature of 20 oC. If the piece of aluminium must not get hotter than 150 oC how much heat energy can it absorb?

6. Why does land heat up more quickly than sea water and how does this help to explain land and sea breezes?

7. Why do you think that houses built of stone take a long time to warm up but once they are warm they stay warm for a long time?

8. Why is water such a good coolant?

9. Tea pots made of china should be heated with hot water before making the tea. This is not necessary with steel ones. Explain this.

10. A pie is cooked in an oven at 200 oC. The aluminium film that covered the pie  can be touched soon after it is removed while the pie is still dangerously hot. Explain this.