Exam 16: Temperature and Heat

In grinding a steel knife blade (specific heat = 0.11 cal/g-C°), the metal can get as hot as 400.°C. If the blade has a mass of 80. g, what is the minimum amount of water needed at 20°C if the water is not to rise above the boiling point when the hot blade is quenched in it?

The coefficient of linear expansion of steel is 12 × 10^-6 K^-1. What is the change in length of a 25-m steel bridge span when it undergoes a temperature change of 40 K?

The coefficient of linear expansion of copper is 17 × 10^-6 K^-1 and that of steel is 12 × 10^-6 K^-1. At 12°C a steel rod has a diameter of 2.540 cm and a copper pipe has a diameter of 2.536 cm. To what temperature must the copper pipe be heated in order for the unheated rod to fit snugly in the pipe?

What is the net power that a dog with surface area of 0.075 m² radiates if his emissivity is 0.75, his skin temperature is 315 K, and he is in a room with a temperature of 290 K? The Stefan-Boltzmann constant is 5.67 x 10^-8 W/(m²·K⁴).

The density of water at 0°C is 999.84 kg/m³ and at 4°C it is 999.96 kg/m³. A 1.0-liter container, full to the brim with water at 4°C is placed in the refrigerator. By the time that the temperature of the water reaches 0°C how much of the water has spilled from the container, assuming that the contraction of the container is negligible?

Two metal spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,

A steel cable spanning a river is 200.000 m long when the temperature is 20.°C. What will be its length when the temperature drops to 0°C? (The coefficient of thermal expansion of steel is 12. × 10^-6K^-1.)

A modern version of Joule's experiment has you turn a crank attached to an 85.0 g aluminum cylinder. A belt exerts a frictional torque on the cylinder of 1.50 Nm. The specific heat of aluminum is 900 J/(kg·K). How many turns of the crank are necessary to raise the temperature of the aluminum by 40 C°?

How much power does a sphere with a radius of 10 cm radiate if is has an emissivity e = 1.0 and is kept at a temperature of 400 K? The Stefan-Boltzmann constant is 5.67 x 10^-8 W/(m²·K⁴).

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are 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 copper, are both attached to a steam chamber, with a temperature of 100°C, at one end, and an ice water bath, with a temperature of 0°C, at the other. The rods are 5.0 cm long and have a square cross-section, 2.0 cm on a side. How much heat flows through the two rods in 60 s? The thermal conductivity of silver is 417 W/(m·K), and that of copper is 395 W/(m·K). No heat is exchanged between the rods and the surroundings, except at the ends.

By what method of heat transfer does a microwave oven transfer heat to the food being cooked?

A person is walking outdoors on a cold day when the temperature is -20°C. Each time he breathes, he inhales 0.0050 m³ of air. He is breathing at the rate of 16 breaths per minute. At what rate does he lose heat from breathing if the air in his lungs is heated to body temperature (37°C) before it is exhaled? The specific heat of air is 1020 J/(kg∙K) and the density of air is 1.29 kg/m³.

Two metal rods, one silver and the other gold, are attached to each other. The free end of the silver rod is connected to a steam chamber, with a temperature of 100°C, and the free end of the gold rod to an ice water bath, with a temperature of 0°C. The rods are 5.0 cm long and have a square cross-section, 2.0 cm on a side. How much heat flows through the two rods in 60 s? The thermal conductivity of silver is 417 W/(m·K), and that of gold is 291 W/(m·K). No heat is exchanged between the rods and the surroundings, except at the ends.

You walk barefoot in your house and cross from the carpeted living room to the tiled-floor kitchen. The tile floor always feels

Platinum melts at 3215°F. What is the corresponding temperature in the Kelvin scale?

A blacksmith is flattening a steel plate, 10 cm × 15 cm × 1 mm. He has heated the plate to 900 K. If the emissivity of the plate is 0.75, what is the total rate of radiation of energy? The Stefan-Boltzmann constant is 5.67 x 10^-8 W/(m²·K⁴). Ignore heat exchange with the surroundings.

Radiative heat transfer requires a fluid to mediate the energy transfer.

The amount of heat that flows through a rod whose ends are held at different temperatures is proportional to the length of the rod.

The coefficient of volume expansion of olive oil is 0.68 × 10^-3 K^-1. A 1-liter glass beaker is filled to the brim with olive oil at room temperature. The beaker is placed on a range and the temperature of the oil and beaker increases by 25°C As a result, 0.0167 liter of olive oil spill over the top of the beaker. What is the coefficient of linear expansion of glass?