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Temperature

Negative absolute temperatures.

Suppose that by some artificial mean it is possible to put more electrons in the higher energy state than in the lower energy state of a two level system (this sort of situation occurs in a laser, for example). Now it is clear that this cannot be an equilibrium situation, but nevertheless, for the time that the system is in the

Macrostates, microstates and temperature of a system.

A hypothetical system contains 16 particles which can occupy nondegenerate equally space energy levels of spacing e. The system is set up so that it has a total energy of 18e, and it is the most probable macrostate, which is shown below: (see the attached file for the chart) (i) How many microstates are there in this mac

A carbon wire and a nichrome wire

A carbon wire and a nichrome wire are connected one after the other. If the combination has total resistance of 11.0 k ohms at 20° C, what is the resistance of each wire at 20° C so that the resistance of the combination does not change with temperature? It seems as though resistivity may need to be considered in order fo

Food processing techniques and preservation principles

What are the differences between (a) Pasteurization, (b) Commercial sterilization, and (c) Ultrahigh temperature processing (UHT). The discussion should be based on the processing method involved and preservation principles behind each method. In addition, what will be the shelf-life expectancy for food products treated by each

Determine the thermal conductivity of the foam

3. A Styrofoam box has a surface area of 0.80m2 and a wall thickness of 2.0cm. The temperature of the inner surface is 5.0°C and the outside temperature is 25°C. If it takes 8.0h for 5.0kg of ice to melt in the container, determine the thermal conductivity of the foam. (Assume that the temperature of the ice is 0°C)

The average thermal conductivity of the walls and roof of a house

1)The average thermal conductivity of the walls and roof of a house is 4.8 x 10"4 kW m"1°C~1 and their average thickness is 21.0 cm. The house is heated with natural gas,with a heat of combustion (energy released per cubic metre of gas burned) of 9300 kcal.m"3. How many cubic metres of gas must be burned each day to maintain a

Adiabatic processes temperature profile.

Please assist in understanding these problems: 1a) If the temperature on the surface over land is 310 K, and the temperature at 0.5 km is 305 K, what is the ambient atmospheric lapse rate? If a parcel of air starts to rise at the dry adiabatic lapse rate, what would be the temperature of the parcel at 0.5 km? Is this ambient

Modeling a situation

Your company was very impressed with your results from the recent study. They have asked that you investigate another location for them and present this new promising location at the upcoming sales meeting. Again, it is your job to check out the various areas and the friendliness for business. One of the factors of interest is t

Tension, Tress in a Pipe Due to Change in Temperature

When the hot water in a certain upstairs bathroom is turned on, a series of 18 "ticks" is heard as the copper hot-water pipe slowly heats up and increases in length. The pipe runs vertically from the hot-water heater in the basement, through a hole in the floor 5.0 m above the water heater. The "tick" are caused by the pipe stic

Determining depth of a lake

At a height of 5 meters above the surface of a freshwater lake, a sound pulse is generated. The echo from the bottom of the lake returns to the point of origin 0.140 s later. The air and water temperatures are 20°C. How deep is the lake?

Ideal gas law problems

A.) At the start of a trip, a driver adjusts the absolute pressure in her tires to be 2.79 105 Pa when the outdoor temperature is 284 K. At the end of the trip she measures the pressure to be 3.02 105 Pa. Ignoring the expansion of the tires, find the air temperature inside the tires at the end of the trip. B.) Oxygen for h

Speed of Sound and the Temperature of the Air

Sound traveling in air at 23 degrees Celsius enters a cold front where the air temperature is 2 degrees Celsius. If the sound frequency is 1500 Hz., what is the wavelength in the warmer air and in the colder air?

Temperature Change

When we add 50.0 mL of 0.250 M HCl to 50.0 mL of 0.250 M NaOH, the temperature increases by 1.71 degrees C and 715 J of heat is evolved by the reaction. Which of the following will be true when we add 100.0 mL of 0.125 M HCl to 100.0 mL of 0.125 M NaOH? A. The temperature change will be 1.71 C and the heat evolved will be 71

Determining the length of a nichrome section

It is desired to make a 1,000 Ohm resistor that does not change over temperature. The resistor is made of a certain length of nichrome wire and a certain length of carbon. Assume a cross section diameter is 1 millimeter for both. Determine the length of the nichrome section in meters.

Energy states and rotational states for molecules at room temperature

3. Probable energy states for molecules at room temperature (a) Suppose we have an system that has the following allowed electronic energy states: 0.2 eV, 2.0 eV, 3.0 eV, 10eV. What is the probability of the system to be at each of these energy states at 350K, 1000K? (b) Suppose we have a system that has the following allo

Heat

Problem: Which would require more heat, melting 500 g of 00C ice or turning 500 g of 1000C water into steam? Problem: A 500g sample of an unknown material requires 750 calories of heat to raise its temperature by 500C. Use equation to solve the problem.

Financial or Public Economic Questions

1. Consider an economy with two people, Henry and Catherine, who consume two commodities, bread and water. Suppose that, due to a drought, the authorities decide to allocate exactly half the available water to each person. In order to prevent one person from "exploiting" the other, neither person may trade away any water to t

Speed of Sound in a Gas

A monatomic ideal gas(y=1.67) is contained within a box whose volume is 2.5 m^3. The pressure of the gas is 3.5 x 10^5 Pa. The total mass of the gas is 2.3 kg. What is the speed of sound in the gas?

Length of Wire To Support a Mass

I have rubber as having a negative coefficient of thermal expansion when it is under tension and that value being -43 x 10^-6/deg K. A rubberband will shrink when heated if it is under tension. The problem has a large rubberband attached to a ceiling, a wire of aluminum of unknown cm. length attached to the hanging end of t

Maximum Thermodynamic Efficiency

A company that produces pulsed gas heaters claims its efficiency is approximately 90%. If the engine operates between 250 degrees C and 25 degrees C, what is its maximum thermodynamic efficiency?

Temperature conversion program

Write a temperature conversion program in Java that converts from Fahrenheit to Celsius. The Fahrenheit temperature should be entered from the keyboard (via a JTextField). A JLabel should be used to display the converted temperature. Use the following formula for the conversion: Celsius = 5/9 x ( Fahrenheit -32) Input of l

Volumetric Efficiency and Delivery Temperature

A single stage double acting air compressor takes in air at a pressure of 1.013 bar and a temperature of 15 C. The air is delivered at a pressure of 7 bar and the clearance volume is 5% of the swept volume. The indicated power of the compressor is 60 kW. Assuming that the compression index, n = 1.3 and that the specific gas con

Two large containers A and B...

Two large containers A and B of the same size are filled with different fluids. The fluids in containers A and B are maintained at 0 C and 100 C, respectively. A small metal bar, whose initial temperature is 100 C, is lowered into container A. After 1 minute the temperature of the bar is 90 C. After 2 minutes the bar is removed