1. A heat engine uses a heat source at 510degreeCelsius and has an ideal (Carnot) efficiency of 24% .

• to increase the ideal efficiency to 41% , what must be the temperature of the heat source?

2. What is the maximum efficiency of a heat engine whose operating temperatures are 670 degreeCelsiusand 360 degreecelcius?

3. To what temperature will 7900J of heat raise 3.0kg of water that is initially at 13.0C? The specific heat of water is 4186 J/kgC.

4. How much heat (in joules) is required to raise the temperature of 32.0kg of water from 14C to 90 degreeC? The specific heat of water is 4186 J/kgC.

5. A. How much energy is required to bring a 1.3-L pot of water at 22 degreeC to 100 degreeC? The specific heat of water is 4186J/kgC.

B. For how long could this amount of energy run a 60-W lightbulb?

6. How much heat is needed to melt 20.50kg of silver that is initially at 21 degree C? The melting point of silver is 961 degree C, the heat of fusion is 88 kJ/kg, the specific heat is 230 J/kgC.

7. High-altitude mountain climbers do not eat snow, but always melt it first with a stove. To see why, calculate the energy absorbed from a climber's body under the following conditions. The specific heat of ice is 2100 J/kgC, the latent heat of fusion is 333 kJ/kg, the specific heat of water is 4186 J/kgC.

a. Calculate the energy absorbed from a climber's body if he eats 0.55kg of -15 degree C snow which his body warms to body temperature of 37 degree C.

b. Calculate the energy absorbed from a climber's body if he melts 0.55 kg of -15 degree C snow using a stove and drink the resulting 0.55 kg of water at 2 degree C, which his body has to warm to 37 degree C.

8. 8. A cube of ice is taken from the freezer at -7.5 degree Cand placed in a 95-g aluminum calorimeter filled with 320 g of water at room temperature of 20.0 degree C. The final situation is observed to be all water at 16.0 degree C. The specific heat of ice is 2100 J/kgC, the specific heat of aluminum is 900 J/kgC, the specific heat of water is is 4186 J/kgC, the heat of fusion of water is 333 kJ/Kg.

• What was the mass of the ice cube?

9.A major source of heat loss from a house in cold weather is through the windows.

Calculate the rate of heat flow by conduction through a glass window 2.0m 1.5m in area and = 3.0 mm thick (Figure 1), if the temperature at the inner and outer surface is 15.0 degree C. Assume that there are strong gusty winds and the external temperature is -9.0 degree C