The loss of body heat via convection is described by which statement? The body gives off waves of heat from uncovered surfaces. An oscillating fan blows currents of cool air across the surface of a warm body. Body fluid in the form of perspiration is vaporized from the skin. The body transfers heat to an ice pack, causing the ice to melt.

In an insulated container, you combine hot metal with ice. The ice starts at -20 degree C. The copper starts at 900 degree C. When 15 kg of the copper is combined with an unknown amount of ice, the system reaches equilibrium as soon as all of the ice has boiled to become steam. What is the final temperature of the copper?

An ice bag containing 0°C ice is much more effective in absorbing heat than one containing the same amount of 0°C water.   (a) How much heat (in J) is required to raise the temperature of 0.900 kg of water from 0°C to 25.0°C?   (b) How much heat (in J) is required to first melt 0.900 kg of 0°C ice and then raise its temperature?   (c) Explain how your answers support the contention that the ice is more effective.

Consider steady heat transfer through the wall of a room in winter. The convection heat transfer coefficient at the outer surface of the wall is three times that of the inner surface as a result of the winds. On which surface of the wall do you think the temperature will be closer to the surrounding air temperature? Explain.

The rate at which a resting person converts food energy is called one’s basal metabolic rate (BMR). Assume that the resulting internal energy leaves a person’s body by radiation and convection of dry air. When you jog, most of the food energy you burn above your BMR becomes internalenergy that would raise your body temperature if it were not eliminated. Assume that evaporation of perspiration is the mechanism for eliminating this energy. Suppose a person is jogging for “maximum fat burning,” converting food energy at the rate 400 kcal/h above his BMR, and putting out energy by work at the rate 60.0 W. Assume that the heat of evaporation of water at body temperature is equal to its heat of vaporization at 100°C. (a) Determine the hourly rate at which water must evaporate from his skin. (b) When you metabolize fat, the hydrogen atoms in the fat molecule are transferred to oxygen to form water. Assume that metabolism of 1.00 g of fat generates 9.00 kcal of energy and produces 1.00 g of…

The interior of the earth is at a higher temperature than it would be if it were cooling steadily; there must be internal sources of heat. Current models of the earth’s interior suggest that one source of heat is the crystallization of liquid iron. Explain how this process provides heat to the earth’s interior.

Consider a 3-m-high, 6-m-wide, and 0.3-m-thick brick wall whose thermal conductivity is k = 0.8 W/m K. On a certain day, the temperatures of the inner and the outer surfaces of the wall are measured to be 14°C and 2°C, respectively. Determine the rate of heat loss through the wall on that day.

In a physics lab, students are conducting an experiment to learn about the heat capacity of different materials. The first group is instructed to add a number of 1.50 g pellets made of lead, at a temperature of 92.0°C, to 305 g of water at 16.0°C. A second group is given the same number of 1.50 g pellets as the first group, but these are now aluminum pellets. Assume that no heat is lost to or gained from the surroundings for either group. (a) If the final equilibrium temperature of the lead pellets and water is 25.0°C, how many whole pellets did the first group use in the experiment? The specific heat of lead is 0.0305 kcal/(kg · °C). pellets (b) Will the final equilibrium temperature for the second group be higher, lower, or the same as for the first group? The specific heat of aluminum is 0.215 kcal/(kg · °C). O higher O lower O the same (c) What is the equilibrium temperature of the aluminum and water mixture for the second group? °C

The same heat transfer into identical masses of different substances produces different temperature changes, due to differences in the heat capacity of the various materials. a) Calculate the final temperature, in degrees Celsius, when 0.85 kcal of heat transfers into 1.05 kg of water, originally at 20.0°C.  b) Calculate the final temperature, in degrees Celsius, when 0.85 kcal of heat transfers into 1.05 kg of concrete, originally at 20.0°C.  c)Calculate the final temperature, in degress Celsius, when 0.85 kcal of heat transfers into 1.05 kg of the steel, originally at 20.0°C.

Problem 11:   A mass m = 125 kg of lava at TH = 1155° C emerges from a volcano deep in the ocean. At this depth, the ocean water is at a temperature of TC = 2.1° C, and the lava cools and solidifies.The specific heat capacity of the lava for this process is c = 840 J/kg⋅°C and the latent heat of fusion of the lava is Lf = 4.0 × 105 J/kg.Assume that the temperature of the ocean does not change in this process. Part (a)  The lava cools to 700.0° C before solidifying. What is the change in entropy ΔS1 of the lava in joules per kelvin during this process? Part (b)  Calculate the change in entropy of the ocean waters ΔS2 in joules per kelvin during the cooling of the molten lava. Part (c)  Calculate the change in entropy of the lava ΔS3 in joules per kelvin when it solidifies. Part (d)  Calculate the entropy change of the ocean ΔS4 in joules per kelvin due to the solidification of the lava.