A 0.298-kg coffee mug is made from a material that has a specific heat capacity of 921 J/kg C° and contains 0.416 kg of water. The cup and water are at 23.8 °C. To make a cup of coffee, a small electric heater is immersed in the water and brings it to a boil in two minutes. Assume that the cup and water always have the same temperature and determine the minimum power rating of this heater. Number i Units

It uses an underground lake  as the cold reservoir of a Carnot heat pump that maintains the temperature of a science lab at 318.5 K. To deposit 11346 J of heat in the lab, the heat pump requires 1108 J of work. Determine the temperature of water in the underground lake, in Kelvin.

A small metal cube with a thermal mass mc and an initial temperature 0 is dropped into a container of water that is actively maintained at a constant temperature 0w. The cube quickly comes to rest on the bottom surface of the container. The bottom surface is maintained at a constant temperature 0 (note that this is different from 0w). The thermal resistance between the cube and the water is Rcw while the thermal resistance between the bottom surface of the container and the cube is RCB. The temperature of the cube is denoted by 0c. a) Draw the system schematic indicating the assumed directions of the heat transfer rates. Label all the nodes and system parameters. b) Derive the governing equation for the temperature of the cube, 0c. c) Where does to appear in the system schematic and how does it affect the governing equations? d) Calculate the steady-state temperature of the cube, css, assuming the following system parameters: 0o = 21°C, 0B = 6°C, 0w = 0°C, Rcw = 2°C/W, and RCB = 4°C/W

A heat pump moves heat from the chilly 8°C air outside a house to the toastier 21°C air inside. The actual coefficient of performance of the system is 3.2, a typical value. How much energy would it take to add 11 kJ each second if the heat pump ran at the maximum theoretical efficiency?

In the comparison of heat and electrical energy flowing along a well insulated conductor which of these is/are true? 1) The Pd across the ends of the conductor is analogous to the temperature difference 44. between the ends of the conductor. 2) The electric current is analogous to the rate of flow of heat 3) The electrical resistance is analogous to the of thermal conductivity

Question 10. A detective has been called to the scene of a crime where a dead body has just been discovered. The detective arrives at 9:00 AM and begins to investigate. Immediately, the temperature of the body is taken and is found to be 90.3°F. The detective checks the programmable thermostat and finds that the room has been kept at a constant 68.0°F for the past 3 days. After the evidence from the crime scene is collected, the temperature of the body is taken once more and found to be 89.0°F. This last temperature reading was taken exactly one hour after the first one. The following day, the detective is asked "At what time did our victim die?" Assuming that the victim's body temperature was normal (98.6°F) prior to death, what should the detective answer?

Three 105.0-g ice cubes initially at 0oC are added to 0.900kg of watter initially at 21.5oC in an insulated container. What is the mass of unmelted ice, if any, when the system is at equilibrium?

A 440 kW of reftigerator working in a room at 35 °C and rejects 450 kj/s. Extimate the temperature of the cooling space.

A 1200 W electric heater has 750 L of water at 100°C in it. How much time will it need to vaporize half of its content? O 10 minutes O 12 minutes O 16 minutes O 14 minutes

A certain coal-fired power plant has a rated power capacity of P = 850 MW. The output of this plant is W = 0.21QH, where QH is the energy input as heat from the hot reservoir. a) Which would increase the efficiency more, doubling QH or reducing QC by half?  b) Calculate the maximum thermal efficiency of the power plant.  c) Calculate the absolute value of the exhausted heat (QC) each second in MJ for the power plant.  d) If the power plant operates for a full day at its rated capacity, how much energy QH in MJ is needed?  e) If, on average, one ton of coal contains Q = 25 GJ of energy, how many tons nH of coal would the plant need to operate for a day at its rated capacity?  f) How many tons nC of this coal is exhausted as wasted heat to QC in a single day?