Specific Definition and 1000 Threads

http://www.youtube.com/watch?v=6u1I5Gwti9s&feature=feedu How exactly do we calculate the age of a star? Is there any speculation as to how this star as existed in this state for so long without producing more heavy elements for so long?

Replacing specific array elements in IDL - solved! Hi I was just wondering if there was any way, other than using FOR loops, to replace specified elements of an array? For example, say A is a 1D array of 50 elements, each equal to 1.0. Is it possible to change say elements 0-9 and 30-49...

Please teach me this: Why specific heat near critical point equals differentiate twice Gibbs free energy with respect to temperature, but not differentiate once with respect to temperature as usually doing. Thank you very much in advance.

Hi, I was thinking of this problem for a couple of hours, but wasn't sure how to formulate it, hence I wasn't able to google it. It's pretty simple to explain, though. Observe any function with a finite integral over the R line \int f(t)dt=A=const. And now look at the function...

Hi guys, I'm struggling with some equations regarding the enthalpy change over a compressor in a vcc system. I'm currently working on a model for the whole system and I think I've got all equations except the one describing the enthalpy difference betweeen the inlet and outlet of the...

Homework Statement I've done 2 experiments, one was to find the specific heat of nickel and the other was to find the latent heat of fusion. For the nickel experiment, it involves heating the nickel in a test tube in a water bath, and then transferring the pellets to a Styrofoam cup. With...

can we determine a specific heat of a sample by cooling it to the temperature of ice rather than heating it to the boiling point of water?

Hi, I would like to study one of Physics or Applied Maths at uni. While I do enjoy maths, I don't think I would like to get too deep into it and would rather much be using it as a tool to do other things. So, at the local university, here's the choices of undergrad programs that I have...

I finally got my GJK algorithm working and now i want to be able to find the depth of the intersection of the two polyhedra in a particular direction (the direction of momentum). I figure the best way would be to find the distance from the origin of the minkowski difference to the hull of the...

i am using dummy nodes for a doubly linked list and trying to get an object at the specified index. for whatever reason, when i test it, i am getting data but it is backwards. for example, when i have a list of integers from 0 to 21, and i attempt to call get(2), i get 19 which is at index 2...

Why do certain elements (particularly transition metals) possesses varying charges in different reactions? For example: Iron (Fe), is known to exist as Iron2+ and 3+.

Homework Statement Give an physical explanation to why the specific heat capacity goes to zero as temperature goes to zero. Homework Equations The Attempt at a Solution I was simply thinking that around absolute zero the average kinetic energy of the particles should be zero...

Hi guys, I have an interesting and difficult problem as follow: Find the smallest number of 12 Ohm resistors (and of course how to connect them) to achieve an equivalent resistor of 7.5 Ohm? I have worked on this problem for many hours but cannot find the answer yet. Somebody can...

It can save your family a lot of suffering and strife. Today my mother-in-law strode out of the house and headed down the street. She got almost to the very busy route 201 before the respite-care worker managed to slow her down until my brother-in-law's girlfriend helped corral her and get...

I think I might have a hard time adequately explaining my issue, but here we go… So everyone knows the Q=mc(delta)T equation, I have this problem that I am working on and it was driving me CRAZY! So I checked out the solutions manual after some time. Basically the stated a mass of copper...

Could I get instructions to help find original research? Looking up research seems to be a laborious process if one is not sure of the exact title.

I have a furnace that is 18"w x18" h x 24" deep. My customer has given me a specific time-temperature curve to hold to, e.g., Heat the furnace from ambient to 1000°F in 10 minutes then to 2000°F over the next 3 hours. The furnace will most likely be heated with natural gas and I would like...

This is my understanding; please, correct me if I'm wrong. If you bombard an atom with em-waves they will never break loose electrons until a certain threshold frequency. At this point the intensity of the light (or the amount of photons) striking the atom is proportional to the number of...

"De-boxing" What does it mean? Is it a term used in tire manufacturing? Or it just means unpackaging, unwrapping, take something out of the box? I need some help, it could also mean "think outside of the box" training, but the article I read has nothing to do with that but everything...

my outlet reads 240 across any two of three leads. Can I assume it is 240 3phase rather than 460 which I also have at the same location. What would 460 read across the leads? Thanks Tom

first off, thanks to any that respond w useful info :) the end answer i need to find on the first topic is how many atoms of hydrogen are required to propel a mass of "x" at an acceleration of 1g in space (assuming no gravitic influence) but i would settle for how to figure out what the fuel...

An interesting electrostatics puzzle! This is a simplification of a real problem I've been hurting my brain on. Luckily the simplification is a fun challenge in its own right. Homework Statement There is a 3D rectangular solid object in space. Each face of the solid is a perfect...

Hi there. We know that Convolve[f,g,x,y] = f[y] if g = diracdelta. My question is, what should be g so that Convolve[f,g,x,y] = f[y1] where y1 is a parameter of the g function. I.e. Is there any function g such that, when convolved with another f, gives the evaluation of f on a given point?

Suppose I have the following equation: P=a*n Where a is a value between 0 and 1. n is the day of the week. (this is just an example) How do I change this expression so, for example, if one were to put 5 for n, the result would be marginally greater than those resulting from inserting any...

A 2.50 x 10^2 kg iron car engine contains water as coolant. Suppose the temperature of engine is 35 degree celcius when it shut off and air temperature is 10degree celcius. The heat given off by engine and watering it as they cool to air temperature is 4.4 x10^6 J. What is the mass of water used...

My problem is this: I have an algebraic expression, and I want to express it in terms of one variable divided by another. It's a fairly large expression, and I'd like to do it in mathematica before attempting it by hand. I've tried Simplify, FullSimplify and Solve, but none of these have done...

Homework Statement In an experiment to measure the temperature of the flame of a Bunsen burner, a lump of copper of mass 0.12 kg is heated in the flame for several minutes. The copper is then transferred quickly to a beaker, of negligible heat capacity, containing 0.45 kg of water, and the...

Can a compound have a high specific heat capacity and be a good thermal conductor, or are these properties mutually exclusive?

Homework Statement Hi, I have a 1Hz pulse and wish to obtain a very short pulse at the low edge of the 1Hz pulse. The following is what I'm referring to: The Attempt at a Solution Since I cannot use a capacitor, I was thinking maybe something with flip flops but I'm still a bit...

Hi :smile: The mass of liquid nitrogen in an open beaker is found to have decreased by 46.3 g in 10 minutes. If the s.l.h of vaporisation of nitrogen at its boiling point is 1.99 x 105, at what rate were the surroundings heating the beaker? Why is the heat capacity of the beaker irrelevant...

Hi, When studying and thinking about the concept of Specific Latent Heat of Vaporization I keep falling in the trap of confusing it with evaporation - in the end, in both cases water in the liquid state is being changed into vapor. Could anyone help me differentiate the two ideas...

An object with mass 30kg and specific gravity 3.6 is placed in a fluid whose specific gravity is 1.2. Neglecting viscosity, which of the following is true? A. The acceleration of the object is (1/3)g and its apparent weight is 100N. B. The acceleration of the object is (2/3)g and its...

So our teacher wants us to find the temperature of a flame of a bunsen burner. To do so, he told us to do the following: Heat an aluminium block of known mass (160g), but unknown initial temperature. Drop it in a beaker with 500 ml of water, of known temperature (22 degrees) and let the...

Hi there, I'm aware that a hypothetical antimatter rocket could have a specific impulse of ~1,000,000 seconds. At first I thought that this would be the highest isp possible as antimatter/matter collision releases all the energy in the mass. However as wikipedia put's it "It is not...

Homework Statement Hi there, I am trying to complete a thermodynamics assignment. I am doing fine until I get to the following question. "Hx = Specific enthalpy at dryness fraction = hf + x . hfg" - I am not quite sure where Hf came from, I guess they want a value for Saturated liquid from...

[An object with mass 30 kg and specific gravity 3.6 is placed in a fluid whose specific gravity is 1.2. Neglecting viscosity, which of the following is true? A. The acceleration of the object is 1\3g and its apparent weight is 100N B. The acceleration of the object is 2\3g and its apparent...

I have this infuriating little problem I'm trying to solve: How many ways are there to produce 2 bucks out of any number of coins? So this means - how many ways to get 200 by adding 1, 2, 5, 10, 20, 50, 100. The best idea I could come up with so far in my research was counting multisets...

Hi, I know very little about maths. I'm struggling to get my head around a question I was asked today, and I was wondering whether someone could explain it to me. Question: If a very large group of kids took it in turns to roll a die again and again until it landed on '1', on average how...

was heated to 86.6 C and then placed in a calorimeter that contained 61.2 grams of water at 19.6 C The temp of the water rose to 21.3 , determine the specific heat of the alloy in J/gC " Technique: use the formula c= q/delta t what do you plug in for q ? you would have c = q/1.7 ? what do you...

50 grams of a substance absorbed 2.578 kj of energy as it changed from 25 degrees celcius to 89.7 What is the specific heat of the unknown substance in J/gC ? Is it correct to use : q = m c delta T q = specific heat m = mass c = ? delta T here is 64.7 The answer seems really big? Is it ...

I am doing a lab about specific heat. i have a cup of boiling water which i put 5 metals into, and a cup of warm water which sits at 22 degrees celcius. i am to record the difference in temperature as i am using the equation Q = mc (delta) T for part one, and then i am using the equation C = Q/m...

Homework Statement How can you calculate the specific heat capacity of an unknown metal? In my question the metal with a mass of 50g and a temperature of 200 degrees celsius was placed in 125 g of water with an initial temperature of 20 degrees celsius. After the simulation and the metal...

Hi, I have been using both ANSYS APDL and ANSYS Workbench (Mechanical) to run analysis on a structure. After loading the structure, in Mechanical i was able to scope my results for deformation and EQUIV stress to just the adhesive layer as this is what I am interested in. However, I can't...

Homework Statement This was a LAB assignment. I need to find the specific heat capacity of a given metal (Cu in this case) in water, I have the following observations. Mass of water: 249.14g = 0.24914 Kg Initial temperature of water: 18 C Initial temperature of metal: 100 C Specific heat...

Or maybe to ask the LOR-writer if they think I'm particularly exceptional on some trait I mention?

Special relativity Length Contraction and Time dilation question Homework Statement Planet X is 18 Light Years from earth, A spaceship moving towards the Earth at a speed of 0.82C (Measured from Planet X) fires a series of 1.2 cm long and 2.1 gram mass (as measured by the pilot) projectiles...

Ok this is a simple question that has made it difficult to figure out. For a visible wavelength of light from a laser source, the beam is visible due to Rayleigh scattering. If the photon is wavelike in classical and macro states then wouldn't that prohibit the coherent nature of a laser beam...

my understanding is that energy is wasted in a solar cells when light with more frequency than necessary to make an electron cross the band gap comes along and the excess energy is converted to heat. does this mean if you only shined blue light at a solar cell which had a perfect electron gap...

Homework Statement A block of weight sits on a plane inclined at an angle \theta as shown. (Intro 1 figure) The coefficient of kinetic friction between the plane and the block is \mu. What is the work done by the applied force of magnitude ? Express your answer in terms of some or all of...

Homework Statement What is the specific heat of seawater? Homework Equations I'm confused about what units are used, and what the specific heat of seawater is defined at? The Attempt at a Solution I found a website quoting, 'specific heat is about 3850 J/(kg C)'