A heat pump with a COP of 2.8 is used to heat an air-tight house. When running, the heat pump consumes 5 kW of power. If the temperature in the house is 7°C when the heat pump is turned on, how long will it take for the heat pump to raise the temperature of the house to 22°C? Is this answer realistic or optimistic? Explain. Assume the entire mass within the house (air, furniture, etc.) is equivalent to 1500 kg of air.

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…

a. Compute the specific heat capacity at constant volume of nitrogen (N2) gas. The molar mass of N2 is 28.0 g/mol. b. You warm 1.15 kg of water at a constant 1L volume from 20∘C to 30∘C in a kettle. For the same amount of heat, how many kilograms of 20∘C air would you be able to warm to 30∘C? Make the simplifying assumption that air is 100% N2. What volume would this air occupy at  20∘C and a pressure of 1 atm ?

The phenomena of "wind chill" is a complicated combination of heat transfer through convection and conduction. The following table estimates the effective temperatures due to wind chill for a variety of air temperatures and wind speeds. a. At what temperature, in degrees Celsius, does still air cause the same effective temperature as -5°C air moving at 15 m/s?