Capacity Definition and 664 Threads

Need a little help, as I seem to have gotten confused. Looking over past exam questions for the heat capacity of a calorimeter, this one is the one I am looking at : A sample of the sugar fructose (C6H12O6) of mass 0.900 gwas placed in a calorimeter and ignited inthe presence of excess oxygen...

They are rated at 1V. Suppose they are in a 40V circuit, and rated to handle 40V. Would they then hold 40x the charge? I tried to calculate it base on electron repulsion, but I remember reading that electrons are not like gasses: they all go to the surface of the material in counter intuitive...

edit: The title is misleading, sorry. Originally I wanted to ask a question about the heat capacity but I figured it out and changed the question while forgetting to change the thread title.. Hi. OK, assume we have a classic magnetic dipole in a magnetic field with ##H= - \vec{\mu} \cdot...

Alright, so looking at how a 40-gauge wire being extremely thin and having high resistance(with respect to it's length), having an extremely short 40-gauge wire(about 1mm), it's possible to maintain 10A or possibly more? I know it's resistance is about 0.002 ohms, which is some what the same...

Homework Statement An open barge has the dimensions shown in the figure. https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/59/59574-46462a33e8dd3e05fa12094d99749d9c.jpg If the barge is made out of 5.2-cm-thick steel plate on each of its four sides and its bottom, what mass...

I know little about the experimental measurements of heat capacity. I can see you'd need to know both how much energy you've transferred to a nanoparticle, and measure the temperature change resulting to ascertain it. This brings me to my questions: How effective is laser heating of...

Hello everyone ! I'm a bit confused about assumption that's made in "Concept in Thermal Physics ; Stephen J. Blundell and Katherine M. Blundell" page 205. It is stated that " Consider a cubic solid in which each atom is connected by springs (chemical bonds) to six neighbours (one above, one...

Homework Statement A 3.50-kg block of iron initially at 8.00 × 10^2 K is placed on top of a 6.25-kg block of copper initially at 4.00 × 10^2 K. Assume the blocks are thermally insulated from their surroundings but not from each other and that they constitute a closed system. How much energy is...

Homework Statement I uploaded a picture of the problem here: http://imgur.com/kD35ROl Sorry about the norwegian text, the problem is this: The three figures with red lines indicate three different energy levels of a system in thermal equilibrium with a reservoir of temperature T. The three...

Lithium ion batteries infamously degrade over time. 1000 charges can cause up to 20% loss in capacity. Is there a type of rechargeable battery that will not degrade over time?

Homework Statement So I've been trying to find the specific heat capacity of the potato for a while and keep coming up with an outrageous number (over 700,000 J/kgC) Here's what I've found mass of potato = 0.15kg initial T of potato = 18 degrees C final T of potato = 83 degrees C (is this not...

Homework Statement Calculate the capacity of the tank.Capacity of the tank when filled to its maximum height in pounds and gallons Maximum height = Gallons: Pounds: ______ gallons*8.34 pounds/gallon*.84 = ______ pounds(note the units again)Calculate the pounds/square foot and pounds/square...

Homework Statement When 1.25 kg of a cold metal at a temperature of 263 K was immersed in 1.43 kg of water at a temperature of 365 K, the final temperature was 336 K. What is the specific heat capacity of the metal? Homework Equations Q=mc∆t -Q=Q[/B] The Attempt at a Solution The answer...

Technically I'm supposed to have a total of 8 optical modes but only 4 of them were seen in a solid (by spectroscopy). So I suspect there's some degeneracies and symmetries involved, but I don't know which ones. I have two sets of assigned degeneracies: frequency; degeneracy set 1; degeneracy...

Homework Statement The diagram shows the molar heat capacity of an ideal diatomic gas and the number of degrees of freedom at different temperatures. Explain why there are 3 discrete plateaus and why the curve is smooth and leaning between them. Homework Equations - The Attempt at a Solution...

Hello PF! I have some questions regarding these concepts. First of all, are the following expressions valid for any case? i.e. any kind of process, like isochoric, isobaric. \Delta U = \int C_v \ dT \Delta H = \int C_p \ dT Or is the ΔU expression only valid when dV = 0, and ΔH when dP = 0...

Consider an ideal gas. For a polytropic process we have ##PV^n = const##. Different values of ##n## will represent different processes; for example isobaric (##n=0##), isothermal (##n=1##), and isochoric (##n=\infty##). The Wikipedia article on polytropic processes states that the specific heat...

The specific heat capacity of water is accepted to be roughly 4.18 J/gK. How would the specific heat value of a given water sample be effected when sediments and other forms of particulation, such as iron oxide from rust, are present? Would the mixture have a higher specific heat capacity value...

What determines the current capacity of a conductor? How can I know the maximum current, any conductor can carry safely, over shot or long durations of time. Example: A conductor that is 1m long, 0.00025m wide, and about 0.003m thick is used to deliver power continuously in a system. How much...

Homework Statement A solid copper cylinder, 50 mm long and of 10 mm radius, is suspended in a vacuum calorimeter. Wound on the cylinder is a length of fine copper wire which is used as heater and resistance thermometer. Initially the resistance of the heater is 100.2 Ω. A current of 100 mA is...

How do I know which one of these two spheres have more specific heat capacity?

Hi, The permanent gases like Nitrogen, Helium etc. have more specific heat capacity as liquid than their gases. Seemingly degree of freedom should reduce in liquid form, and therefore, specific heat capacity must reduce in liquid form. But this isn't the case. I remember reading somewhere...

I have been looking into a number of things related to Reaction Engine's Sabre Engine Program for their Skylon hypersonic aircraft. I find the program absolutely fascinating as the technological development looks like it is on track to revolutionize air and space flight in the coming decades...

Homework Statement A pot on a stove burner contains 10kg of water and an unknown mass of ice at equilibrium at 0degC at time = 0min. During the first 50mins, the mixture remains at 0degC. From 50 to 60mins the temperature increases to 2degC. What is the initial mass of ice? Ignore the heat...

I need to compute for the relief capacity (gpm or lb/hr) of a 10" rupture disc with relief valve set at 180psig. Vented out into the atmosphere. Assume fluid is water at 140F. I tried using ASME and API Equation but they give different answers. Can someone tell me the correct answer and what...

Homework Statement Find the mass of water that vaporizes when 3.39 kg of mercury at 243 °C is added to 0.476 kg of water at 90.0 ° Homework Equations q=mcT, q=mL The Attempt at a Solution When vaporising T=100degC. Heat lost by mercury = heat gained by water. 3.39kg x 139J/kg/C x...

Hello i have a noobquestion: does a polymer ion battery lose capacity faster when charged and discharged at the same time??

Homework Statement I have an "abstract" problem. Calculate the maximum cooling capacity for forced air cooling of a room. The room contains two computers that each has a energy usage of 1 kW. v_air_in=75m^3/h v_air_out=30m^3/h Homework Equations As the cooling is done by ventilation...

I need to find a high capacity (60-90 gpm) pneumatic pump that is able to pump 2.8 cP (fairly low viscosity) dirty water reliably. there's no need to worry about discharge pressure or suction head, because the level in the vessel provides plenty of head pressure. I had a vendor propose a...

There are numerous references to the basic equation for the torque capacity of a keyed shaft, but I can find absolutely nothing for a simple D-shaped shaft (ie a plain shaft with a single, plain, parallel flat milled on it) with a D-shaped hub. No set screw. It seems so simple but there's...

Homework Statement the answer is c) but i can't figure why ! is the more heat capacity substance lose and gain energy faster than the other one so it take more energy to get it's temperature raised by the same amount because it lose most of it very fast during the heating process ?

Homework Statement (a) Given V, α, κT, μJT, and CP, calculate CV at 90.0 bar and 308 K for carbon dioxide gas. (b) If carbon dioxide's vibrations were fully excited, then CV would be 4R. What's the percent vibrational excitation at 90 bar and 308K? Homework Equations Both constant pressure...

Dear Friends Is there a good battery capacity measurement device you can recommend? I need to measure how much capacity a lithium pack really has. Thanks. regards Ramone

I have been looking for specific heat capacities of certain materials such as steel but i can never find a solid answer, so i figured i would test it myself, how would one test specific heat capacities?

Hey I am a physics student, and not so familiar with chemistry. I have a huge problem, because I have to find the following 3 values for liquid isopropanol: 1. The specific heat capacity at constant volume 2. The specific heat capacity at constant pressure 3. Volumetric Isobaric...

Calculate the change in entropy of the Universe as a result of the following operations: (a) A copper block of mass 0.4kg and thermal capacity 150JK-1 at 100◦C is placed in a lake at 10◦C. dS=dQ/T dQ=mCdT Tried simply combining these equations and integrating to find change of entropy of...

Hello, I finished an experiment of finding out the track spacing of a CD and a DVD. My laser wavelength was 654nm which I used to calculate track spacing of the optical discs. I got a track spacing of a CD 1.57um which is close to a real value of 1.6um, and the track spacing of a DVD...

hey :smile: I am a college student and am looking for a liquid having the following properties at very low temperatures (probably around 100-150 K) - 1) Very high density 2) Very high temperature of vaporization 3) Less- Volatile 4) High specific heat capacity

Homework Statement Here is the question: I am confused about the solution. In the solution they found that the minimum capacity rate ratio R = C_min/C_max was zero. This is because of the term I circled in the red which I do not understand why it goes towards infinity. Here is the solution...

Hi, I am looking for an introduction to heat capacity measurements at low temperature (10K). (For example for producing the linear dependence of the electronic heat capacity on T). I fail to find a simple introduction. Can anyone mention keypoints or a good source? Thank you!

Hi. I am trying to develop a cone clutch for torque transmission. I have looked a lot over the internet but I cannot find how to calculate the maximum torque transmission capability of a cone clutch. Everywhere they use the equations with inputs of axial force. I want to find the maximum torque...

If I use the un-threaded section of a 3/8th inch bolt as a pin to lock a sprocket hub to a drive shaft I would drill and ream so that the bolt would need to be lightly tapped to go through the assembly. If the fit was looser (.025 thousands clearance) would that reduce the capacity of the...

Homework Statement Using the Debye dispersion approximation, calculate the heat capacity of a harmonic, monatomic, 1D lattice. Next, find the temperature dependence in the low temperature limit. (Assume that the longitudinal mode has spring constant CL = C, and the two transverse modes both...

Homework Statement I have an ideal gas of n=1023 point particles with a constant pressure of P = 3x105 Pa as 200J of heat flows into it. What is the heat capacity at constant pressure, CP? Homework Equations CV = (ΔU + PΔV)/ΔT The Attempt at a Solution Okay... So I have N, P and Q...

Homework Statement 1 mole of an ideal gas initially at 100° C and 10 atm is expanded adiabatically against a constant pressure of 5 atm until equilibrium is re-established. Given that the temperature dependence of the heat capacity is CV = 18.83 + 0.0209T calculate deltaU, deltaH and deltaS...

Hello All, would anyone know an expression for the heat capacity of an ideal gas, moving with relativistic speeds. For non-relativistic gas, the heat capacity is a constant, proportional to R (the universal gas const) Many thanks.

Homework Statement I am confused about what the difference between specific heat and heat capacity is. I have a block of metal (Aluminium) which I had to record dimensions and calculate the heat capacity of the block. I am just wondering am I doing the correct calculation? Homework...

Homework Statement A 30.0g block of ice at 0.00°C is dropped into 500.0g of water at 45.0°C. If the process was carried out in an iron container with a mass of 150g what would the final temperature be? Homework Equations Q=mc(T2-T1) Heat Lost = Heat Gained Specific Heat of Water: 4200 Specific...

"cold capacity" We are taught the notion of heat capacity in undergraduate physics and how different materials can hold a different maximum of heat energy per unit volume. Is there an opposite notion? Obviously heat is energy, so cold is just lack of it... but my intuition tells me that if I...

Consider a dielecrtic with polarization P=(a+b/T)\epsilon and heat capactiy C\epsilon=A+B\epsilon, where a and b are constants. Show that B=2bV/T2 and find the isothermal dielectric constant \kappael. Use properties of G(T,\epsilon) I'm really not sure where to start with this one. Any help...