Thermal Definition and 1000 Threads

A worker pushed a 23 kg block 13 m along a level floor at constant speed with a force directed 22° below the horizontal. If the coefficient of kinetic friction between block and floor was 0.40, what were (a) the work done by the worker's force and (b) the increase in thermal energy of the...

Homework Statement A ring of aluminum has a hole in the middle. When the ring is heated: a) the hole decreases in diameter b) the aluminum expands outward and the hole remains the same size. c) the area of the hole expands by the same percent as the area of the aluminum. d) the area of...

Hi there, I have came across a question in past exam papers that basically asks... What do the terms Conversion and breeding mean? I put conversion is the change from a fissionable element to a fissile element such as U238 to Pu239. When more of these fissile products are created than used...

Homework Statement Consider a system in thermal equilibrium consisting of N particles that have 2 energy states E1 and E2 separated by an energy ΔE. Given that $$N_1 = \frac{N}{exp(-ΔE/k_BT)},\,\,N_2 = \frac{N exp(-ΔE/k_BT)}{1+exp(-ΔE/k_BT)}$$ show that in the case of the lowest energy...

The rod is made of A-36 steel and has a diameter of 0.25 in and a length of 4 ft. Attached to each end of the rod is a spring which is fixed to a wall. If the springs are compressed 0.5 in. when the temperature of the rod is T=40 F, determine the force in the rod when its temperature is T=160 F...

Homework Statement For science fair, I'm doing a project in which we are trying to calculate the force of a thermometer being moved normally, versus a thermometer being slowed down by a high-friction material. The thermometer will (Potentially) read the amount of thermal energy produced by...

Dear people, it might be a simple question, but I have been on this for over 2 days now and can't find a proper explanation of this anywhere: https://dl.dropbox.com/u/2264519/circuit.jpg Picture a RCL circuit which is kept at room temperature. Now even when there is no current going through...

Hello i have a problem with this question if anyone could help me ,that would be great. Estimate the thermal velocity of particles in the solar corona (take a distance two times the radius of the sun and assume that the particules have only two degrees of freedom), thus the thermal energy is...

This is a general question. In struggling hard in my stat and thermal physics course, especially with homework from kittel and kroemer. I am looking for another book that would have more examples so that I can have an easier time with home work problems. Would anyone have any suggestions ?

Hi all, This is my first post in PF. This is a heat transfer problem.I have started to learn the basics of Heat transfer (I'm in 3rd yr engg).My project coordinator has allocated a problem and I'm having tough time solving it. The Problem statement :(Pl find the attached images) The...

How would I calculate thermal exchange rate of Air for different amounts of humidity? I'd like to create a graph to show how much radiant heat air would absorb, (at some temperature (10°C) changes depending on the humidity amount, 0 - 100%

Hi, I'm doing 'Heat and Mass transfer' at college and we're covering the topic on the hydrodynamic and thermal boundary layers. I have a couple of questions, the answers to which are not given explicitly in any of my textbooks. 1. During open flow, why does laminar flow eventually have...

Homework Statement Explain why electrons carry a net energy but not a net current in the case of thermal conduction. Homework Equations n/a The Attempt at a Solution n/a Please help me understand this!

Hello all.. I know this thread is asked a lot before and i read some of them.. but to make sure that i understand and to make like a small resume can we say: Heat is the "quantity" of the thermal energy being exchanged? i mean its like the work that is responsible for the change of the kinematic...

Homework Statement 250.0g of copper at 100.0°C are placed in a cup containing 325.0g of water at 20.0°C. Assume no heat loss to the surroundings. What is the final temperature of the copper and water? Homework Equations Conservation of Energy [SIZE="3"]mcCΔTc = mhCΔTh The...

I'm trying to understand the origin of thermal radiation. All things with a temperature emit electromagnetic radiation. Every discussion I've found starts with that as a premise and then goes on to Wien's displacement law and Planck's law, etc which I follow. But *why* do all things...

Homework Statement The equation F/A = -Y\alpha\Delta T gives the stress required to keep the length of a rod constant as its temperature changes. Show that if the length is permitted to change by an amount \Delta L when its temperature changes by \Delta T, the stress is equal to F/A = Y(\Delta...

Homework Statement Compute the change in internal energy, ΔU, and the final temperature, Tf, when 1 mole of an ideal, diatomic gas is compressed adiabatically to 89.700% of its initial volume. The starting point is 22.500°C and 16.100 L. (Assume that the vibrational degree of freedom stays...

Homework Statement 2)Both, a brass tube and the steel rod located inside the brass tube are solidly attached to common end plates A and B at either end. The respective diameters are : Do = 5.4 [cm] Di = 3.0 [cm] d= 2.8[cm] Brass: alpha=19x10^-6/degree celcius E=210GPa Steel...

Homework Statement One end of a metal rod is maintained at 100°C, and the other end is placed in a large container with ice and water at 0°C. The rod has length 50 cm and a cross-sectional area of 0.8 cm 2 . The heat conducted by the rod melts 4 g of ice in 5 minutes. Calculate the...

Hi guys, could you concretely explain me (also with a simple example) the difference between blackbody emissive power (sometimes found as e'λb) and blackbody radiation intensity (i^{'}_{λb})? and which the difference between a diffuse surface and a surface that follows the Lambert law? Thank...

Homework Statement As shown in attachment a steel cable is stretched between two poles. In 20°C temperature the cable remains horizontal (the length of the cable 10m). At a higher temperature θ°C the cable bends like in attachment. The lamp hanging from the mid-point could be...

Author: Frederick Reif Title: Fundamentals of Statistical and Thermal Physics Amazon Link: https://www.amazon.com/dp/1577666127/?tag=pfamazon01-20 Prerequisities: Table of Contents: 1. Introduction to Statistical Methods Random Walk and Binomial Distribution / General Discussion...

Hello, I have looked through various websites, which show single glazing heat losses (U-factor) to be 5.7 W/m^2.K. But when I use thermal conductivity basic formulas, the yielded results are quite different: k of glass is 1.05 W/m.K; L -> glass thickness is 4 mm = 0.004 m; so: U = k/L =...

Homework Statement from this video: It showed that a better conductor of heat will transfer heat as well as absorb heat more quickly than a lousy conductor. However, during the transfer the heat is passed from eg metal at 30 degrees to a solid at 20 degrees . So why would the metal being a...

A heat transfer of 9.5 x 10^5 J is required to convert a block if ice at -15°C to water at 15°C. What is the mass of the block of ice? So do I have to use the equation; Q= mcΔT ? and Q= mL ? And if so how do I use it?

A 97.6-g lead ball with an initial temperature of 20°C, is dropped from rest from a height of 4.57 m. The collision between the ball and ground is totally inelastic. Assuming all the ball's kinetic energy goes into heating the ball, find its final temperature. PLEASE HELP ME UNDERSTAND THIS...

At a local county fair, you watch as blacksmith drops a 0.050-kg iron horseshoe into a bucket containing 25.0 kg of water. If the initial temperature of the horseshoe is 450°C, and the initial temperature of the water is 23°C, what is the equilibrium temperature of the system? Here is...

Hi! I am reading Molecular Driving Forces, 2nd ed., by Dill & Bromberg. On page 53, example 3.9, we consider why energy exchanges between two systems from the point of view of the 2nd law. We consider two separate systems. Each has ten particles, and each particle has two possible energy...

as we know that atomic collisions are perfectly ellastic perfectly ellastic collisions are given by v1=u1(m1-m2)+2(m2)u2 / m1+m2 and v2=u2(m2-m1)+2(m1)u1 / m1+m2 when m1=m2 v1=u2 v2=u1 we know heat is stored in the form of vibrational energy(kinetic energy) so to exchange energy...

Homework Statement I learned that the heat capacity is the amount of energy absorbed to raise the temperature of a body by 1 degrees. While conduction is the process of heat transfer by vibrations. That being said, when I supply 1000N of heat to 2 rods of different material but same mass the...

Hey all, i'm trying to set up a thermal model of a permanent magnet synchronous electric motor. This by doing a lumped system analysis of the motor. In the thermal network that I've set up, I'm trying to introduce an equivalent thermal conductivity value (W/mK) for the copper conductors plus...

hi, i m new to this forum,this is my first post,i have recently started studying heat transfer. i m am little bit confused about the origin of thermal radiation in human beings.i mean radiations are emitted when an electron jump from a shell/orbit which is far from the nucleus to a shell which...

hi All, We know from QM that black bodies at temperature T emits light in a well stabilished patern. Now what if the body has color? Which is the emission patern of a green snooker ball for example, at temperature T? When scattering white light we see this ball green because it absorbs...

I'm making a Minecraft mod, and I need a bit of help. Quite simply, it simulates heat transfer. Unfortunately, I don't know enough about the subject to construct a good model. Here's what I have so far: Looking back, I can see that simulating heat in terms of watts is probably a really silly...

Hi! I'll be covering the above book next semester and was wondering if there is anything I should be particularly aware of about thermal physics. -aLearner

Hi guys. I was wondering, what happens to the temperature of a object if it's put into vacuum? Say you have a box of steal (something that transfers thermal energy fast between the inside and outside). Inside the box you have a rock. The rock is held in the center of the box using...

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...

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...