Thermal Conductivity
Physics ⇒ Heat and Thermodynamics
Thermal Conductivity starts at 9 and continues till grade 12.
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See sample questions for grade 9
A house has walls made of brick (k = 0.6 W/m·K) and glass wool insulation (k = 0.04 W/m·K). Which material will allow more heat to pass through, assuming equal thickness and area?
A material with a thermal conductivity of 0.1 W/m·K is used to make a wall 0.5 m thick. If the area is 4 m² and the temperature difference is 10 K, calculate the rate of heat transfer.
A metal rod is heated at one end. After some time, the other end also becomes hot. This is an example of which type of heat transfer?
A metal rod of length 1 m and cross-sectional area 0.01 m² has a thermal conductivity of 200 W/m·K. If the temperature difference between its ends is 50 K, calculate the rate of heat transfer.
A wall has an area of 10 m², thickness 0.25 m, and is made of a material with thermal conductivity 0.2 W/m·K. If the temperature difference across the wall is 30 K, calculate the rate of heat transfer.
A wall is made of a material with low thermal conductivity. What is the main advantage of this in a house?
Calculate the rate of heat transfer through a wall 0.2 m thick, area 2 m², thermal conductivity 0.04 W/m·K, and temperature difference 20 K.
Describe one practical application of a material with high thermal conductivity.
Explain why a woolen blanket keeps you warm in winter.
Explain why double-glazed windows are better insulators than single-glazed windows.
Explain why metals feel colder than wood at the same temperature.
If a metal rod and a wooden rod are both heated at one end, which will transfer heat to the other end faster?
State the formula for the rate of heat transfer (Q) through a slab of material in terms of thermal conductivity (k), area (A), temperature difference (ΔT), and thickness (d).
What is thermal conductivity?
Why are cooking pots often made with copper bottoms?
Why do engineers use materials with low thermal conductivity in the construction of spacecraft?
Why is polystyrene foam used in coolers and refrigerators?
A copper rod and an iron rod of the same length and cross-sectional area are joined end to end. The free end of the copper rod is kept at 100°C and the free end of the iron rod is kept at 0°C. If the thermal conductivity of copper is 400 W/m·K and that of iron is 80 W/m·K, which rod will have a steeper temperature gradient? Explain your answer.
A refrigerator door is made of two materials: steel (k = 50 W/m·K, thickness = 0.002 m) and polyurethane foam (k = 0.02 W/m·K, thickness = 0.05 m). Which layer provides more resistance to heat flow? Show your calculations.
A student wraps a metal rod and a plastic rod of the same size with identical cloth and places one end of each in boiling water. After 5 minutes, the exposed ends are touched. Predict and explain which rod will feel hotter and why.
