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Thermodynamics and Statistical Mechanics
Thermodynamics is the study of energy conversion between heat and mechanical work which leads to the macroscopic properties such as temperature, volume, and pressure. Statistical mechanics is the application of probability theory to study the thermodynamic behavior of systems of a large number of particles.
1,125 Questions
Why steady state heat transfer doesnot change with respect to time?
Steady-state heat transfer does not change with time - because - that is the definition of steady-state, i.e. "steady-state" means "does not change with time".
As for why heat transfer might be steady state - that would be a consequence of the driving forces and physical conditions remaining constant with time. For example:
Heat source remains the same temperature
Heat sink remains the same temperature
Heat source remain in the same position relative to each other, both in terms of distance and orientation.
Surface areas of heat source and heat sink remain the same.
Any intervening medium remains the same composition, temperature, density, and pressure.
If convection is occurring, flow rates remain constant.
If radiative heat transfer is occurring, any intervening medium has constant transmissivity, reflectivity, and absorbtion.
If radiative heat transfer is occurring, radiating and absorbing surfaces maintain constant radiative and absorbing properties.
There are a few other factors that can influence steady-state heat transfer, but these are a good description of the most important ones.
How many electrons does mercury consists in outer orbital?
Mercury's atomic number is 80. Thus, it has 80 protons and 80 electrons to be neutral. Its configuration is therefore 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10. As you can see, 6 of its s orbitals are filled.
Why does gases obey the gas law only in high temperature only?
The ideal gas law effectively treats atoms as point masses that have no interactions except for collisions (no attraction or repulsion). Molecules in hot gasses generally are so far apart that their volume relative to the overall volume is insignificant. They don't attract or repel each other much either at high temperatures because they are mostly too far apart - and - they are moving so quickly that even when close, they are not close for long. As gases cool, the molecules group closer together and move slower and quit behaving in a manner that the ideal gas law can be said to represent well.
How can heat transfer through matter?
Hot matter and cold matter differ by the kinetic energy the atoms/molecules have. Temperature (as measured on the absolute temperature scale) is proportional to the average kinetic energy of the particles in a material.
Normally we classify movement of heat according to three processes, thermal conduction, radiative transfer and convection.
Heat transfer by Convection occurs in a fluid because it moves and the heat energy contained in the fluid moves with it. This is very important in home insulation and the main reason we insulate walls with fibers to inhibit motion of the air. Radiative transfer of heat occurs when the hot object emits electromagnetic radiation (light) and that electromagnetic radiation carries its energy elsewhere. We can see light energy that came from the sun or even a light bulb, but there is much more energy at longer wavelengths in the infrared part of the spectrum that we can't see. Radiative energy travels through materials (like air) that are transparent, or nearly so, for the particular part of the spectrum carrying the heat. (The distribution of energy emitted as light changes with the temperature of the object doing the emitting which is why we say something is "white hot" meaning it is at a high temperature.)
It is heat transfer through conduction that we observe when we say heat travels through a solid body. If one part of an object it hotter than another, the molecules in that part have more kinetic energy. If left undisturbed, heat energy in a hot spot gradually spreads out into the whole object through thermal conduction of heat. Thermal conduction is nothing more that the energetic particles having collisions with their less energetic neighbors and thereby passing on some energy
to them. The process happens many millions of times a second between neighboring molecules so only small amounts of energy need transferred from a "hot" molecule to a cooler neighbor for the over all process of neighbor to neighbor transfer to effectively carry that energy from a hot spot to cool spots. Eventually, the temperature of an isolated object will become uniform through this process of intermolecular energy transfer which we recognize as thermal conduction.
What is sensible heat without moisture?
Sensible heat is the heat required to raise the temperature of a substance.
When determining the heat of a vapor, moisture must be considered as it removes heat from the vapor (in order to heat the moisture [water vapor] to the ambient temperature). Dry steam has no moisture. Dry air has no moisture (a physical improbability).
Air normally has moisture determined as relative humidity. This humidity [water vapor] must be heated with the air. Then the moisture heat absorption must be subtracted from the whole to determine the heat absorption of the air without moisture, expressed as heat per unit per degree (often 0.24 btu per dry standard cubic foot per degree F for air). Any moisture in the air increases the heat necessary to raise the temperature by about 1 btu per pound of moisture per degree F. (0.004 btu per gram of moisture per degree F).
This increased heat requirement becomes more evident as air is compressed, and the moisture is removed by condensation.
Which of the following statement is represent of the second law of thermodynamics?
One statement that represents the second law of thermodynamics is that heat naturally flows from an object at a higher temperature to an object at a lower temperature, and that this process is irreversible without external intervention.
Why do your feet feel colder when you get into a pool using second law of thermodynamics?
Your feet feel colder when you get into a pool because heat naturally flows from areas of higher temperature to lower temperature to reach thermal equilibrium. When your feet are exposed to the cooler water, heat is transferred away from your feet into the water, making them feel colder. This is a result of the second law of thermodynamics, which states that heat will always transfer from a warmer object to a cooler object until thermal equilibrium is reached.
How do you use manometer to measure level?
A well-type manometer is to be used to measure differential pressure in a water flow system. The manometer uses a special bromide liquid of specific gravity of 2.95.The well and tube are of 75 mm and 5 mm diameter respectively. The scale placed along the tube has no correction factor for the area ratio of the manometer. Calculate the value of this factor which must be multiplied by the manometer reading in mm to find the pressure differential in kg/cm2.
Not sure exactly what you are asking but you do it the same way as a 4 digit number
only the answer needs to have 3 decimal places in it when you are done.
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There may be different reasons for multiplying by 1.732, depending on the specific
situation in which you find yourself at that moment, which unfortunately you have
neglected to describe for us.
All I can tell you is that in general, whenever you need the square root of 3 and you're
in a hurry, you can use 1.732 in that emergency and the inaccuracy of your result
will be less than 3/1000 of 1 percent.
What properties of liquids make it support heavier objects like a thin film over it?
Liquids have cohesive forces that allow them to stick together and provide surface tension. This surface tension can support lighter objects by creating a thin film that can hold them up. Additionally, the viscosity of liquids helps to stabilize objects placed on their surface by preventing them from sinking.
Whether you could cool a kitchen this way depends on whether you could get the heat coming off the external coils out the windows and whether the air outside is cooler than the exterior coils of the fridge. In all likelihood most of the heat coming off the coils would stay in the kitchen (rather than going out the windows) and rather than cooling it, you would heat up the kitchen while the refrigerator compressor continued to run (until the compressor burned out from continuous operation). Remember that a refrigerator cools the inside of the fridge by pumping the heat out of the interior of the fridge and into the room - in this case the kitchen.
Which metal conducts less heat?
The least conductive elemental metal is Neptunium (atomic number 93) with a conductivity of 0.063 W/cm·K. Plutonium (atomic number 94) is only slightly better, with a conductivity of 0.0674 W/cm·K. Note that both Neptunium and Plutonium are radioactive and members of the Actinoids.
Next in conductivity is Manganese with a conductivity of 0.0782 W/cm·K. Few people will encounter Neptunium or Plutonium, but manganese is a much more common metal and non-radioactive.
Note that sometimes some of metalloids are included with metals since they may form alloys with metals. The least conductive metalloid is Telurium with a conductivity of just 0.0235 W/cm·K. A metalloid is a chemical element with properties that are in-between or a mixture of those of metals and nonmetals, and which is considered to be difficult to classify unambiguously as either a metal or a nonmetal. There is no standard definition of a metalloid nor is there agreement as to which elements are appropriately classified as such.
Mixtures of metals, aka alloys, have conductivities somewhere in between the most and least conductive included elements, so the least conductive metals will be elemental - as will the most conductive metals.
A cartographic chart is a navigational map used by ships and aircraft to facilitate safe travel on the water or in the air. It displays important information such as water depths, coastlines, navigational aids, and other features to help pilots and sailors navigate accurately.
The name of the single thermodynamic quantity is Gibbs free energy (G). The symbol for Gibbs free energy is ΔG (delta G). The sign of ΔG determines whether a reaction is spontaneous (negative ΔG) or non-spontaneous (positive ΔG).
The second law of thermodynamics states that in a closed system, entropy tends to increase over time. However, the process you described would require a significant decrease in entropy, which goes against this law. In a solid, the particles are held together in a fixed arrangement by forces such as bonding and intermolecular forces, which prevent them from spreading out to fill the available space.
Can perpetual motion be achieved using a pendulum in a vacuum?
Yes. In a vacuum, the only resistance is the friction in the suspension for the bob of the pendulum. Other than that, it should swing a long time. In air, friction with air will add to the friction in the suspension and it won't swing as well as it would in a vacuum. But it will swing for a while. A pendulum will swing in water, but the hydrodynamic drag will make it stop in a really, really short period of time. Just a couple of swings will strip the pendulum of almost all its energy. And the speed of the pendulum will be slower than in air, and it won't swing anywhere nearly as far through the bottom of its arc as it did in air.
What is the difference between mechanics and thermodynamics?
Mechanics deals with the motion of objects and the forces acting on them, while thermodynamics focuses on the relationships between heat, work, and energy transfer. Mechanics is concerned with the behavior of macroscopic objects, while thermodynamics looks at the macroscopic properties of systems in equilibrium.
What does high heat do to enzymes?
High heat can denature enzymes, disrupting their structure and functional shape. This can render the enzymes inactive or reduce their efficiency in catalyzing biochemical reactions. Additionally, prolonged exposure to high heat can lead to irreversible damage to enzymes.
What is the SI unit of Thermal power?
The SI unit for power, thermal or mechanical, is the watt, W.
1 W = 1 J/s (joule/second).
What is an equation of state of a thermodynamic system?
An equation of state is one that relates "state" variables. A state variable is one that only depends on the current state of a system, not how you got there. Examples of state variables include (but are not limited to); Temperature, Pressure, Internal energy (or specific internal energy), density (or its reciprocal, specific volume), enthalpy, Gibbs free energy, entropy, and fugacity. These are in contrast to path variable such as Work and Heat. To calculate the change in a state variable, you only need to know the beginning and ending states. Because it is not path dependent, we often do the calculations in pieces along a hypothetical path were we know how to calculate each change and then add them up. The path we calculate does not need to be the actual path taken. Contrast this with calculating the work done along a path - where the path is everything.
An example would be calculating a change in elevation for a car. You could calculate it by taking a hypothetical path where you drop it from its current elevation to sea level and then raise it from sea level back to its final elevation. Contrast that with figuring out how much gasoline it would take to drive it from a farm in the hills down to the coast and then back up into the mountains. The work for that path would be different from taking a road straight from the farm up into the mountains. The change in elevation from start to finish would still be the same though - elevation is a state function and calculations of elevation are state functions.
Some of the commonly used equations of state deal specifically with the relationship between the Pressure, Temperature, and Volume (or specific volume) of a system - especially gases. Examples include:
Ideal Gas Law
PV = nRT
Van derWaals
(P + n2a/V2)(V - nb) = nRT
Redlich-Kwong
P = RT/(Vm - b) - a/[√T · Vm(Vm + b)] where Vm = V/n, the molar volume
Others include the Soave modification to Redlich-Kwong, Wilson, and Peng-Robinson.
Not all of these equations work well under all conditions. The Ideal Gas Law fails as systems become cold and dense. The Wilson Equation fails to predict the existence of liquid/liquid immiscibility (like oil and water). None of the above equations of state describe solids - that requires still other equations of state.
Sink temp, or sink temperature, refers to the temperature of a heat sink, which is a device that helps transfer heat away from a component or system to prevent overheating. Maintaining a lower sink temperature is crucial for efficient heat dissipation and proper functioning of electronic devices.
The Second Law of Thermodynamics states that a system with no energy input and no losses will tend towards a zero energy state. This is essentially the entropy of any energy exchange. Thus, you require a constant input of energy to maintain any system.
Why does it improve the accuracy of the experiment it Tf Tr equals Tr Tw?
When Tf Tr equals Tr Tw, it improves the accuracy of the experiment because it allows for an efficient transfer of heat energy between the sample (Tf), reference (Tr), and the surroundings (Tw). This ensures that the temperature readings are stable and reliable, eliminating any potential errors or fluctuations in the measurements. This consistency in temperature conditions helps to enhance the precision and reliability of the experimental results.
What is cooling rate and how is it measured?
Cooling rate refers to the speed at which a material loses heat during the cooling process. It can be measured by monitoring the temperature of the material over time using a thermometer or sensors. The cooling rate is influenced by factors such as the material's thermal conductivity, its surface area exposed to the surrounding environment, and the temperature difference between the material and its surroundings.
