Exam 16: Temperature and Heat

Two metal rods are to be used to conduct heat from a region at 100°C to a region at 0°C as shown in the figure.The rods can be placed in parallel,as shown on the left,or in series,as on the right.When steady state flow is established,the heat conducted in the series arrangement is

An object having a fixed emissivity of 0.725 radiates heat at a rate of 10 W when it is at an absolute temperature T.If its temperature is doubled to 2T,at what rate will it now radiate?

A temperature change of 20°C corresponds to a Fahrenheit temperature change of

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper,with the aluminum and the copper in thermal contact.The specific heat capacity of aluminum is more than double that of copper.Which object experiences the greater magnitude gain or loss of heat during the time the system takes to reach thermal equilibrium?

Two metal rods,one silver and the other gold,are attached to each other end-to-end.The free end of the silver rod is immersed in a steam chamber at 100°C,and the free end of the gold rod in an ice water bath at 0°C.The rods are both 5.0 cm long and have a square cross-section that is 2.0 cm on a side.No heat is exchanged between the rods and their surroundings,except at the ends.How much total heat flows through the two rods each minute? The thermal conductivity of silver is 417 W/m ∙ K,and that of gold is 291 W/m ∙ K.

An aluminum rod is 10.0 cm long and a steel rod is 80.0 cm long when both rods are at a temperature of 15°C.Both rods have the same diameter.The rods are now joined end-to-end to form a rod 90.0 cm long.If the temperature is now raised from 15°C to 90°C,what is the increase in the length of the joined rod? The coefficient of linear expansion of aluminum is 2.4 × 10^-5 K^-1 and that of steel is 1.2 × 10^-5 K^-1.

A giant star radiates energy at the rate of 3.0 × 10³⁰ W,and its surface temperature has been measured to be 3000 K.Assuming that it is a perfect emitter,what is the radius of this star? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

By what length will a slab of concrete that is originally 18 m long contract when the temperature drops from 24°C to -16°C? The coefficient of linear thermal expansion for this concrete is 1.0 × 10^-5 K^-1.

Which one of the following quantities is the smallest unit of heat energy?

A hole in a brass plate has a diameter of 1.200 cm at 20°C.What is the diameter of the hole when the plate is heated to 220°C? The coefficient of linear thermal expansion for brass is 19 × 10^-6 K^-1.