A thermal column (or thermal) is a column of rising air in the lower altitudes of Earth's atmosphere, a form of atmospheric updraft. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. The Sun warms the ground, which in turn warms the air directly above it. A thermal is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically.
Consider a rod of length 'l'. When heated, its temperature got increased by 't'.
Increase in its length = l\alphat.
total length be (l1) = l + l\alphat.
Again the rod is heated and the temperature further got increased by 't'.
Total length be l2.
l2 can be calculated in two ways,
l2 = l1 +...
Homework Statement A hot reservoir is maintained at a temperature of 78 oC, and a cold reservoir is maintained at a temperature of 5oC. They are separated by 11.00 cm, and are connected by a cylindrical bar made of two materials. The radius of the bar is 0.83 cm. The upper part of the bar is...
Homework Statement
The figure below shows a block that consists of two materials with different thicknesses l 1 and l 2 and different thermal conductivities λ1 and λ2. The temperatures of the outer surfaces of the block are Thigh and Tlow, as shown in the figure. Each face of the block has a...
Homework Statement
An ideal gas is at 40°C. The gas is cooled, reducing the thermal energy by 35%. What is the new temperature in °C?Homework Equations
I'm not sure there is one? The Attempt at a Solution
Since, in an ideal gas, thermal energy is proportional to temperature, I multiplied 40°C...
Homework Statement
An ice cube at its freezing point is placed in nested Styrofoam cups which contain 240g of water at 21.5 degrees C. If the final equilibrium temperature when the last trace of ice melts is 15 degrees C, what was the mass of the ice cube?
Homework Equations
mCΔt = -mCΔt...
Homework Statement
It is said that good ice skating only occurs when the ice below the skates melts. Using the Clausius-Clapeyron equation, estimate the coldest temperature at which good ice skating can occur. (Water expands 9% on freezing, Latent heat of ice melting is 334 kJ/Kg, the contact...
Homework Statement
While forming a 1.5kg aluminum statue, a metal smith heats the aluminum to 2700 degrees C, pours it into a mould, and then cools it to a room temperature of 23.0 degrees C. Calculate the thermal energy released by the aluminum during the process.
Homework Equations
Q =...
Homework Statement
According to experts good tea can only be made at temperatures greater than 96 degrees celsius. If this is true, can you brew good tea at elevation 4.5km (Pressure = 6.2*10^{4}Pa) . Given that latent heat of vaporisation for water is 2.4*10^{6} J/kg and water has a molar...
Thermal physics- Can you make good tea at a certain pressure!?
Homework Statement
According to experts good tea can only be made at temperatures greater than 97 degrees celsius. If this is true, can you brew good tea at elevation 4km (Pressure = 6.2*10^{4}Pa) . Given that latent heat of...
Hi All,
I'm working on a Hydraulic Tire Curing Press Project.There are Hydraulic cylinders in many regions of the press.Steam @ 220 deg c is used to heat the tire to bring about vulcanization process.The press earlier supplied to the customer had thermal insulation problems due to which the...
Homework Statement
A solid's thermal expansion coefficient is defined as
δ= \left(\frac{1}{V}\frac{∂V}{∂T}\right)
In the Debye model and at the low-temperature limit, show that δ is a positive quantity and is proportional to T^{3}. At the high-temperature limit, show that δ is still...
Homework Statement
a) estimate the number of phonons in a 1mm cube of a crystal at 10K, taking a sound speed of 1000m/s.
b) estimate the frequency ω for which you will find the highest phonon nrg content in the range of ω to ω+dω. (Again, assume low temps). Give your solution in the form...
Hi everyone.
I was wondering if there is a convention for solving heat conduction problems. Specifically should one account for thermal expansion? The SI units for thermal conductivity are W/m/K. Does m include thermal strains already?
It seems for basic problems it would be easier to...
Hi all
I'm doing a project for energy efficient buildings with thermal insulation.(Just a leisure project and I am not technically that strong!)
This is about thermal radiation shielding.
My understanding is that Aluminium has higher reflectivity (Hence lower emissivity ) so that it...
1. Jupiter radiates more energy than it receives from the Sun by 8.7x10-10L0. Jupiter's radius is 7.0x109cm and its mass is 1.9x1030g. Compute its thermal time scale. Could gravitational collapse power this luminosity for Jupiter's entire lifetime of 4.5 Gyr?
2. Kelvin-Helmholtz (aka...
I was reading a book, 'Introducing Quantum Theory' by J.P.McEvoy, and I find it difficult to understand in details of Maxwell Distribution, Thermal Equilibrium, Fluctuation, Wein's law and Planck's quantum theory, so I am finding it difficult to follow Einstein's explanation of photoelectric...
Homework Statement
A coffee machine in a café passes steam at 100°C into 0.18kg of cold coffee (s.h.c. the same as that of water(4200j/kg/K)) to warm it. If the initial temperature of the coffee is 14°C, what mass of steam must be supplied to raise the temperature of the coffee to 85°C Homework...
Hello..
The query is regarding thermal conduction of heat from a solid body:
Suppose we have a long metallic rod which is insulated on the curved surface and one of the bases. If we supply Q amount of Heat for a small time to the rod from the non-insulated end, initially the temperature of...
Hello everybody,
I am solving a 2D problem of thermal stresses in a rectangular plate in which temperature is changing only y direction. Plate has fixed displacement conditions. Could anyone help me to find out analytical solution of thermal stresses for my problem? Does anyone suggest me...
Homework Statement
A 1.0 sample of nitrogen gas (diatomic)is heated at constant pressure from 300K to 420K, Cp (nitrogen) = 29.1 Jmol-1°C-1
The thermal energy transferred to the gas is?
1. 8370 J
2. 12,200 J
3. 34.90 J
4. 3590 J
5. 12.20 J
Homework Equations
KE = 1/2mv2 =...
Consider a 47000K object that emits thermal radiation.
How much power does it emit per square meter?
What is its wavelength of peak intensity?What formula do I use to solve these questions?
I'm currently having a bit of an intuitive problem understanding the Prandtl number effect on boundary layers and I'm hoping that someone can explain it better than what I've read in some heat transfer books.
According to various HT books, a low Prandtl number means that heat diffuses quickly...
So I have to write out nodal equations for a system that I was given, and I started off by drawing out the flow diagram to see where everything was. I'm having trouble starting the nodal equations though.
The attachment has 2 diagrams: figure 1 is the correct diagram that models the thermal...
Homework Statement
Part 1: I have a cylinder of radius R and lengh L. At first i can assume that we have expansion in both R and L. And that i can use the linear thermal expansion coefficient(\alpha) = 4 \times 10^{-6}. The relative change in R and L is 1 \times 10^{-4}, and from that i have...
Hi Everyone,
Does anyone know of a tool that can extract thermal neutron cross-section data from endf for all availible isotopes? I'm trying to help my professor compile some data to modernize one of his courses. I'm trying to find a list of capture and scattering cross-sections for a wide...
Homework Statement
A container is divided into two parts by a thermally conducting wall. There are N atoms of a monatomic ideal gas on the left side, 2N on the right. The gas on the left is initially at absolute temperature 200K, the gas on the right at 500K.
a. After thermal equilibrium...
Homework Statement
A non-isotropic material is heated, fractional increase in length is different along different directions. With length l1=6.1 cm and l2=6.0 cm. In direction of l1, the coefficient expansion is \alpha1= 10×10-5 K-1 and direction l2 is \alpha2= 40×10-5K-1. The plate is heated...
Homework Statement
(B) http://imgur.com/VL4aG
although I showed the rest of the problem for context if needed
Homework Equations
ΔL=αLΔT
The Attempt at a Solution
I'm a little confused by the wording of the problem. When we find the shift in ΔN, are we actually finding Δ(ΔN)...
Homework Statement
In an experiment, a small radioactive source must be moved at extremely slow speeds. A positioning device based on thermal expansion was devised where the radioactive source is attached to one end of an aluminum rod and a heating coil is wrapped around a selection of the rod...
Homework Statement
Two cars collide head on while each is traveling at 80 km/h. Suppose all their kinetic energy is transformed into the thermal energy of the wrecks. What is the temperature increase of each car? You can assume that each car's specific heat is that of iron.
Homework Equations...
A couple questions:
I'm in the process of making some small amplifiers and using bjt's in the small signal realm. I have used bjt's as switches for quite a while, so I am quite familiar with their basic operation. I was reviewing small signal analysis trying to refresh my memory about how...
IF I am in error, forgive me. but I had this thought cross my mind today.
IF absolute 0 is the stopping of all atomic (or molecular) movement.
and you induce a thermal reaction, i.e. splitting the nuclei. would the reaction be slowed down at all?
(to make a slow burn)
Yea. I understand...
Homework Statement
Show that at constant volume V and temperature T but decreasing number N=n*N_{A} of particles the Van der Waals equation of state approaches the equation of state of an ideal gas.
Hint: Rearrange the equation of state into the explicit functional form P=P(v,T) and use x=1/v...
I had a thermal conductance homework problem where heat flowed through gold, and then silver. Both materials were of the same length and same cross sectional area. The problem mentioned that the energy transfer had reached a steady state, and I found through doing the problem that under these...
Homework Statement
A set of telephone lines is to be installed so as to connect town A to town B. The town A has 2000 telephones. If each of the telephone users of A were to be guaranteed instant access to make calls to B, 2000 telephone lines would be needed. This would be rather extravagant...
Homework Statement
A number is chosen at random between 0 and 1. What is the probability that exactly 5 of its first 10 decimal places consists of digits less than 5?Homework Equations
Binomial Coefficient = \displaystyle \binom{N}{n1}
Where n1 denotes "n1" objects of an indistinguishable type...
Hi all,
I have a heat sink for which I know the exact geometry (have the CAD model). This heat sink was custom designed and machined from a hunk of aluminum, though it is very basic and I have a hunch I can find an extrusion or OTS part that will match its performance. Rather than trying to...
A vertical cylindrical container contains some helium gas that is in thermodynamic equilibrium with the surroundings. The gas is confined by a movable heavy piston. the piston is slowly elevated a distance H from its equilibrium position and then kept in the elevated position long enough for the...
in winter, wooden floor feels cold to the barefoot but the rugs and carpets don not feel cold although the floor and carpet are at the same temperature?
Just a quick question relating to thermal equilibrium between a hot and cold body. If a hot body and cold (closed systems) are opened up to each other, the thermal energy will be transfer from the hot body to cold body through conduction. So even when thermal equilibrium is reached, the...
Homework Statement
Coefficient for thermal expansion for glass is β1 = 25x10^-6 K^-1
Coefficient for thermal expansion for this particular liquid is β2 = 300x10^-6 K^-1
The glass cup is completely filled with the liquid at 4.0 L. The temperature of the glass and liquid both increased by...
Suppose we have two separate containers of helium gas in thermal equilibrium and completely isolated from the rest of the universe. Let's assume the containers are ideal in the sense that they are completely tranparent to all electromagnetic radiation.
Since helium is monatomic, the only...
Hi guys,
I'm having a bit of trouble with following thermal equilibrium question...
Homework Statement
Create an equation representing energy transfers of thermal energy equilibrium, that will enable one to determine the latent heat of fusion for ice.
One conducts an experiment mixing ice...
\inthi all,
I need just little bit of confirmation about what I'm doing.
Normally I know how the stiffness matrix is composed for 2 node frame element in 3D space. which creates 12x12 matrix for that element, if there is also thermal loading on frame element additional...
Homework Statement
I am working on this ahead of my fall class and don't actually want the answer...
just pointers to help me understand something.. Thanks guys! :)
I am really rusty with my general physics and calculus knowledge =(
The original question asks me to prove that, for a...
If I sleep on copper would there be any beneficial release of negative Ions to improve my well being. In addition, will the thermal properties of copper stabilize my body temperature at 37.5c.
Homework Statement
A hole in an aluminum plate has a diameter of 1.178 cm at 23 degrees Celsius. (a) What is the diameter of the hole at 199 degrees Celsius? (b) At what temperature is the diameter of the hole equal to 1.176 cm?
Homework Equations
The coefficient of linear expansion (α)...