Exam 20: Thermal Properties and Processes

You are testing thermal conduction through two different materials, A and B, of the same cross-sectional area. Material A is twice as thick as material B, and the thermal conductivity of material A is three times higher than that of material B. What is the thermal resistance of A divided by the thermal resistance of B?

The coefficient of linear expansion for a certain metal is $\alpha$ . The coefficient of area expansion for a square plate made of the same metal is approximately

Two types of wall separate a refrigerated room from the rest of a building. Wall 1 has half the thermal conductivity of wall 2. Wall 2 is half as thick as wall 1. The two walls have the same area. The rate of heat flow through wall 2 compared with the rate of heat flow through wall 1 is

An object at temperature 227 ^$\circ$ C radiates energy at a net rate of R J/s. By what factor would the net rate of energy loss increase if the same object were at a temperature of 427 ^$\circ$ C? Assume the surrounding temperature is 0 ^$\circ$ C.

The graph shows isotherms of a gas plotted from van der Waal's equation. At which point is a mixture of liquid and vapor likely to be found?

Under some conditions, real gases depart from Boyle's law due to

The triple point of a substance gas is

If the absolute temperature of an object is tripled, the rate at which it radiates thermal energy

The axes on a phase diagram are

A sheet of metal has a star shaped hole. What happens to the distance, d, when the temperature of the sheet is increased?

The gas tank of your car can hold 60 L of gasoline. Do you get more gasoline in terms of the number of moles when you fill your tank when the gasoline is cold or hot? The coefficient of volume expansion for gasoline = 930 $\times$ 10^-6/K and that of steel is 33 $\times$ 10^-6/K.

If the temperature on the warmer side of a wall is doubled, the rate at which heat is conducted through the wall

A change in temperature of 100º C causes a square plate to expand as shown in the figure. The coefficient of linear expansion of the plate is approximately

If the absolute temperature of an object is doubled, the rate at which it radiates thermal energy

A change in temperature of 100º C causes a square plate to expand as shown in the figure. The coefficient of linear expansion of the plate is approximately

A scuba tank of volume 40 L is filled with 200 moles of compressed air at a pressure of 100 atm. What is the volume occupied by O₂?

A square hole, 30 cm on each edge, is cut in the center of a square aluminum plate 1 m on a side. The coefficient of linear expansion of aluminum is 2.4 $\times$ 10^-5/Cº. If the plate is heated 25 ºC above the starting temperature, the area of the hole

The coefficient of linear expansion of the steel in a certain bridge is 1.10 $\times$ 10^-5/Cº. If at a minimum winter temperature of -30ºC the bridge is 30.5 m long, at the summer maximum of 40ºC its length is increased about

The length of an object varies with temperature according to L = -5T + 3T³ The coefficient of linear expansion of this object is

The wall of a house consists of three layers: a wooden outer wall with an R factor of 1.0, a 3-in layer of fiberglass insulation with an R factor of 11, and a gypsum-board inner wall with an R factor of 0.33 (all R factors are in h · ft² · Fº/Btu). When the temperature is 68ºF inside the house and - 4.0ºF outside, what is the rate of heat loss through an 8-ft by 15-ft section of this wall?