# Principles of Technology

## Thermal Resistance (4:4)

### Review Worksheet

If you understand and can do these problems you should do well on the quiz.

1. There are 2 formulas used to calculate thermal resistance. List both and define the variables.

2. List the units of thermal resistance in both the English and SI systems.

3. "k" represents the value for thermal conductivity. What does this mean, and give an example of materials with good and bad conductivity values.

4. The outside air temperature is 8 deg. C and you want to keep it at 26 deg. C inside your house. To do this you need to keep your heater running at an output of 2550 kilocalories per hour. What is the overall thermal resistance of your house?

5. A shop building has a thermal resistance of 0.075 C deg. / (kcal/hr). If the difference between the inside and outside temperatures is 27 C deg., what is the building's overall heat flow rate?

6. An 1/8" thick aluminum plate which has 0.75 ft2 of surface area is used to transfer heat from a stove to a frying pan. What is the thermal resistance of the plate?

7. Using the values from #6, calculate the heat flow rate if the temperature difference across the plate is 35 F deg.

8. Given: a plate glass window 1/4" thick with a surface area of 8 ft2. Calculate thermal resistance across the glass if the outside air temperature is 110 deg. F and the inside temperature is 68 deg. F.

9. Using the values from #8, calculate the heat flow rate.

10. Using values from #8, calculate the heat flow rate using a different method than you used in #9.