IB PHYSICS GOHS
CHAPTER 11.1-11.2 WORKSHEET (TOPIC 3.2)
1. If the thermal capacity of a quantity of water is 5500 J oC-1, how much heat is required to raise its temperature from 22oC to 98oC?
2. If 3200 J of heat is lost from a block of metal with a thermal capacity of 800 J oC-1, then what is the initial temperature of the metal if its final temperature is 22 oC?
3. The thermal capacity of a 60 kg human is 210 kJ oC-1. How much heat is lost from a body if its temperature drops by 2oC?
4. The temperature of a room is 10oC. In 1 hr the room is heated to 20oC by a 1 kW electric heater. (Hint: Power = Work/time)
a. How much heat is delivered to the room?
b. What is the thermal capacity of the room?
c. Does all this heat go to heat the room?
5. The specific heat capacity of water is 4200 J kg-1 oC-1. How much heat will be required to heat 300 g of water from 20oC to 60oC?
6. A metal block of mass 1.5 kg loses 20 kJ of heat. As this happens, its temperature drops from 60oC to 45oC. What is the specific heat capacity of the metal? What metal is this block most likely made of?
7. How much heat is required to raise the temperature of 250 g of copper from 20oC to 160oC?
8. The density of water is 1000 kg m-3.
a. What is the mass of 1 dm3 of water?
b. How much energy will it take to raise the temperature of 1 L of water from 20oC to 100oC?
c. A water heater has a power rating of 1 kW. How many seconds will this heater take to boil 1 litre of water? (Hint: Power = Work/time)
9. A car of mass 1500 kg travelling at 20 m s-1 brakes suddenly and comes to a stop.
a. How much KE does the car lose? (KE = ½ mv2)
b. If 75% of the energy is given to the front brakes, how much energy will they receive?
c. The brakes are made out of steel and have a total mass of 10 kg. by how much will their temperature rise?
10. The water comes out of a shower head at a temperature of 50oC at a rate of 8 litres per minute.
a. If you take a shower lasting 10 min, how many kg of water have you used? (1 L = 1 kg)
b. If the water must be heated from 10oC, how much energy is needed to heat the water?
ANSWERS
1. 418,000 J
2. 26 oC
3. 420,000 J
4. a) 3,600,000 J b) 360000 J/Kg oC c) No, some is lost to the environment
5. 50,400 J
6. 889 J/Kg oC; Aluminum
7. 13,500 J
8. a) 1 Kg b) 335,000 J c) 335 s
9. a) 300,000 J b) 225,000 J c) 50 oC
10. a) 80 Kg b) 13,000,000 J