Calculations Definition and 982 Threads

Suppose I want to find the ground states corresponding to several Hamiltonian operators ##\left\{ \hat{H}_i \right\}##, which are similar to each other. As an example, let's take the ##\hat{H}_i##:s to be anharmonic oscillator Hamiltonians, written in nondimensional form (##\hbar = m = 1##) as...

Homework Statement "A straight, nonconducting plastic wire ##x=9.50_{10^{-2}}m## long carries a charge density of ##λ=1.3_{10^{-7}} C/m## distributed uniformly along its length. It is lying on a horizontal tabletop. If the wire is now bent into a circle lying flat on the table, find the...

How accurate do you think NASA's eclipse calculations are? Will that aircraft provide accurate moon trajectory?

As a note, this is my first post on this site. I was looking at some bouyancy calculations with regard to balloons being in air when I came across this post. I cannot understand why the calculation for the net force of bouyancy done by Vintage (the last post on the page) does not include the...

This particular question is for an assignment. However, I believe that I have the final (correct) answer, but want to check the understanding. I am required to calculate the resistance of the secondary winding of a transformer. The transformer is a 415:11000 V step-up, rated at 200kVA but with...

I've been trying to understand how we know that the observable universe is flat, and I'm having difficulty finding any sources that explain exactly how the calculations were done. On this WMAP website (https://map.gsfc.nasa.gov/mission/sgoals_parameters_geom.html), it says: "A central feature of...

Hello everyone! I have seen several DIY projects which successfully gathered heavy water from normal water. For example Cody from codys lab used electrolysis to "enrich" the water. This however is a messy process. So i became curious, if this can be done easier by centrifugation. Based on...

Hello, 1- IF we have an object has 200 kg and we also have a machine has 5 kg and pushes that object with force of 600 n , in Newton third law it must be another force =-600n then : the acceleration of the object must be 3 m\s^2 and the acceleration of the machine is 120 m\s^2 , Am I wrong...

I am not really buying my calculations of a gearboxes rpm for some conveyor applications. First conveyor has to travel 30 feet in 4.5 minutes with 2" rollers. If I divide 30' by 4.5minutes I get 6.667feet/minute and with a 2" diameter the gearbox should be about a 12:1 ratio. The other is a...

Hi, everyone! I'm trying to find the period of a satellite orbiting the Earth by the next formulas with: miu= 398600.5; a=36770.48 km; I. 2*pi*(a^3/miu)^1/2 II. 84.489*(a/Re)^(3/2)min III. 0.00016587*a^(3/2)min And I got aprox. 19 hours from both formulas (I. and III.) which is correct. Can...

Homework Statement . Consider a pump that is required to compress air in a factory. The cylinder in the pump has an inner diameter of 2.00 cm and length 60.0 cm. Air is drawn into the pump at atmospheric pressure and 18 degrees celcius and the pump adiabatically compresses the air to a pressure...

I am trying to calculate the forces (in Newtons) between a permanent magnet, and an electromagnet. All I can find is interactions between permanent magnets, electromagnets, but never both and it is getting really confusing for me to do the calculations. So basically, if I have a permanent...

Homework Statement :[/B] The density of a 2.05 molar solution of acetic acid is 1.02g/ml. The Molality of the solution is: (a) 1.14 mole/kg (b) 3.28 mole/kg (c) 2.28 mole/g (d) 0.44 mole/kg Homework Equations :[/B] The Attempt at a Solution :[/B] I tried it out very simply using unitary...

I'm interested in calculating density of states (DOS) and band structures for metals in which the electrons have a finite temperature (up to ~ 3 eV). I've read several papers indicating that the DOS shifts with electron temperature, and that DFT can be used to calculate finite-temperature...

Hi! I am a bit confuzzled by these equations given by a highly referenced and cited paper I have been using to create a spreadsheet I have been working on. The equations are: PV=mRT Where P is the cylinder pressure, m is the mass of gasses in the cylinder, R universal gas constant of the gas...

Hey Guys, so I'm just in need of some help in relation to finding the output current after the voltage has been dropped to 6V. The circuit has an input voltage of 24V and I've attached a photo of my circuit diagram. Hopefully I haven't made any errors in that, but I've tested the circuit and it...

a train accelerates uniformly from rest to a speed v m/s with uniform acceleration a m/s^2 it then decelerates uniformly to rest with uniform retardation 3a m/s^2. the total distance traveled is s metres. if the average speed for the whole journey is square root (s/2) find the value of a. does...

Hi, I was looking into Doppler shift calculations, and I came across this blog post. It gives a very simple and straight forward account of calculating the velocity of a star. Following is the summary the blog post: Spectrum of Alpha Centauri (A. Cen.) is obtained through Lhires III...

Hi! I'm currently doing a project where I'm constructing a framework for an engine mount connecting an airplane with an engine. The project involves both calculations by hand and with CAD(Creo), and i have no problem with the CAD part as i have done the simulations. The part with doing...

I know these calculations in thermodynamics can be done by hand or a simple calculator but I wonder if some programs do these calculations. These programs might be called multiphysics programs. An example of a calculation - select piston-cylinder arrangement. -enter initial...

Hi everyone! I was wondering if there is a known equation to calculate how the speed of a fan affects the cooling of a heat source. Is there a way to calculate this or know what type of relationship it is? Thanks!

Hi everyone! I'm having a problem with calculating the fermionic propagator for the quantized Dirac field as in the attached pdf. The step that puzzles me is the one performed at 5.27 to get 5.28. Why can I take outside (iγ⋅∂+m) if the second term in 5.27 has (iγ⋅∂-m)? And why there's a...

So my chemistry teacher said that: Moles of a compound = mass of the sample (grams) ÷ molar mass of the compound (grams/mol) So how do i get from there to the equations mol = g x (mol/g)?? I would like to know the steps involved i.e. rearranging the equation, dimensional analysis Thanks!

Does anyone know of a good library in javascript that would help to develop technically accurate animations? I know there is stuff in python, but I'd like things to happen in the browser. Apart from linear algebra with complex valued matrices and vectors, I'd like to have things like numerical...

It's been like 3 or 4 years since I've built an electric motor & I've forgotten mostly everything and need some help getting this worked out for those that don't mind. I'm trying to build a 48V 40-60A eBike motor. I'm using 200C 10AWG Magnet Wire. I have a 24 pole stator core. The stator core...

Homework Statement With reference to the diagram attached. i) What would be a suitable value for Rg and why ii) If the drain current is 2mA, determine a suitable Q-point on the mutual characteristics and hence obtain a value for Rs[/B] The Attempt at a Solution i) I chose a 2.2M ohm resistor...

Homework Statement The bottom of the boat has dimensions a = 50 m, b = 10 m, the height of the ship is c = 5m. Impact created in the bottom a circular hole with a diameter d = 20 mm. The initial height of the upper edge of the ship above the water level is h = 3.5 m. The ship is empty and open...

Dear Everyone, We are a research group doing research in computational sciences. We are considering ordering new computers for our research. I was wondering if anyone could advise us regarding the hardware specifications needed to run heavy and time-expensive programs, specifically in...

Hello everyone, I am working on a 3.2 meter wing span electric aircraft with another group of 30 engineering students. In calculating the induced drag and lift for preliminary calcs I am a little confused as to whether I need to include the width of the fuselage in the wing span(b) for induced...

I seem to be stuck in a rut and so I was hoping you guys could help me out with this should-be easy question.. The pontoon dimensions are (L x W x H) 114.84m X 15m X 3.4m. Made of concrete. There is about 1m of freeboard so I figured using the water displacement, the structure weights about...

I'm in the process of designing a part which must be submerged down to 2000m (200 bar/20 MPa/ 2900 psi). A sketch of the part has been attached. The outer housing will be titanium and the inner part aluminium. I've carried out the calcs for the outer part to withstand the external pressure, but...

Homework Statement How to calculate the average given the uncertainties in each measurement 8.70 +/- 0.28, 9.680 +/- 0.046, 9.700 +/- 0.055, 9.720 +/- 0.067? Homework EquationsThe Attempt at a Solution I know I add the values and divide by 4. I also know I add the absolute uncertainties but...

Hello everyone! I am currently having some real issues estimating the power requirements for a concept vehicle's Air-Conditioning System, and I mean I've been going over this on and off for the better part of a fortnight. At this stage I feel like I have fried my brain and have no idea if I am...

The project I'm building involves a 12 V electric motor connected to a spindle lifting a 20kg weight. The radius of the spindle is 2cm, so the torque applied by the weight is 0,02m*20kg*9,8m/s^2, which gives me 3,92N*m. So, my 12 V motor needs to deliver 3,92N*m just to keep the weight steady...

I know the rules to experimental uncertainties with addition and subtraction, but what about division? For instance here The light bulb was measured to have 1.27 ±.05V by the DMM in parallel. Using the DMM in series, its current drawn was .202 ±1A. As a result its resistance was approximately...

Homework Statement Could someone help point out certain conceptual errors in my interpretation of the mirror clocks time dilation thought experiment? Say S' is the frame of reference traveling at speed V w.r.t to frame S, which means that events happen at the same coordinate in S'. We know...

Homework Statement A 415V to 11 kV transformer has a rating of 200 kVA. The winding resistance and leakage reactance when referred to the primary are 0.014 ##\Omega## and 0.057 ##\Omega## respectively. (a) Determine the % regulation of the transformer at 0.8 power factor lagging. (b) In...

Hello, My name is Molly. I am looking for help with Basic Engineering Calculations and how to understand them. This is not homework and certainly not for anything dangerous or anything I am building. I simply have developed a fascination for the subject and a strong desire to understand the...

I interest the software, which understands gamma and sigma matrices, that the convolution can go over Lorentz indexs, and over group indexs, which understands what is covariant differentiation, trace. I tried to use maple, but work goes with difficulty. Although I write convolution over...

So, I am new to here and I am currently a technician that does vacuum systems for the semiconductor industry (mainly Electrical). I came across something today that has me quite perplexed. So We have this system that flows gas through 1/4" stainless tubing to a pump to dilute gasses and...

Suppose I have a motor driving a shaft that runs 1.5m long with a screw attached, the screw is mixing a product. Power = Torque x Speed Torque = Power/Speed To find my Torque I can use my Shear Max = Tr/J And J for a shaft is Tmax = (π / 16) τmax D3 My question is, where does the mass of the...

Hi Everyone, I am having trouble grasping the concept of Raoult's law, partial pressures etc. One problem in specific is: A system contains 3 moles of methanol and 7 moles of water at 25 degrees celsius. The temperature is raised until there is 40 mol% methanol in the gas phase. How much is...

When calculating the moment of inertia for a rotating object, why is "dr" not incorporated into the integral? However, dm is part of the integral, isn't the distance from the axis of rotation changing as well? Hence shouldn't the integral involve both dm and dr?

Homework Statement Here's a similar problem to the one in my book (I don't want to post the one in my book as I don't want to cheat): The gravitational acceleration on Mars is 3.719[m/s^2]. The gravitational acceleration on Earth (excluding air friction and other places) is 9.81. the initial...

Sir, Guide me about calculation of hydrolics of fountain which is having throw of 60 feet and 90 feet with delivery pipe size of 50 mm. Regards Bankar

Hi guys, I'm trying to use the CASTEP software for dft calculations. I have plenty of documentation on how to use it once it's all up and running, however I don't know how to get to that point :/ I'm not the best with linux but I've manually installed programs before through tarballs but here...

hi guys, i wanted to know all the calculations needed to to know if my electric drill will drill through a wall or not?

Homework Statement V1 = 10cos(10^4t) V2 = 5cos(10^4t + pi/3) Time Base setting = 0.1msec/div By how many divisions will these two traces differ? Homework Equations W = 2pi/T[/B] The Attempt at a Solution W = 2pi/T T = 2pi/W W = 10^4 T = 0.628 milliseconds 0.628milliseconds/(0.1msec/div) =...

is there any decent free simulators or software for doing the massive integrals involved with square of wave functions, the area under the square of them. transition probabilities, average position etc for systems more complex than a particle in a box.

Homework Statement Calculate the complex power delivered by the source V = 12cos(wt) V Homework Equations V = IR The Attempt at a Solution 1. I combined 8ohm resistor and 8j ohm inductor in parallel to get 4+4j ohms 2. I combined that with 4ohm resistor in series to get a Zth of 8+4j ohms 3...