Per Definition and 545 Threads

Homework Statement Given the relationships: Xpu = MVAbase / MVAfault Xpu = ( MVAbase / MVArated ) * ( X% / 100 ) MVAfault = sqrt(3) * V * Ifault Xohms = [ V / sqrt(3) ] * Ifault Homework Equations Show that: Xpu = [ MVAbase / V^2 ] * Xohms The Attempt at a Solution No matter how I...

Why is the speed of light 186,000 miles per second? Is that how fast the ether will allow it to travel? and if that is the case, if the edge of the universe; the edge to which the universe is speeding up, would the ether out there let light travel at higher or lower speeds? Which to me means...

MODERATOR NOTE: THERE IS NO TEMPLATE BECAUSE THIS THREAD WAS ORIGINALLY MISPLACED IN A NON-HOMEWORK FORUM Viscous liquid (ρ = 1460 kg/m3, μ = 5.2×10−1Ns/m2) is pumped through a smooth pipe with a 0.1 m diameter, at a rate of 5×10−2m3/s. Using your Fanning friction factor versus Reynolds Number...

Homework Statement If you have a ring of charge, is it valid to say lambda = Q/L, or is it lambda = dQ/dL? Homework EquationsThe Attempt at a Solution

Homework Statement [/B] If 5 percent of the power of a 100 W bulb is radiated in the visible spectrum, how many visible photons are radiated per second? Homework Equations E=hf=hc/λ The Attempt at a Solution I know how to solve this, I just wanted to make sure. I will take 5 W or J/s as the...

Hey all I am a newbi and wondering how to do this conversion. When i see a water pump which is 1400G/hour at that rate what would be the psi? For example my garden hose is about 40psi and at that rate it would mean a curtain g/ph based on say a 15mm outlet radius. Im trying to figure out what...

Hello forum, I will be an undergrad senior majoring in mathematics. Instead of taking the ordinary 5-course workload, I am thinking of doing 3 courses per semester and postpone graduation by an year. But I am wondering if by doing so my graduate application is going to be affected negatively. I...

I'm looking into the Math in Moscow and have a very simple question which I can't seem to find answered online: Roughly how many students participate in the Math in Moscow program in a given semester?

Homework Statement https://dl.dropboxusercontent.com/u/88040310/powerhw3.png 1. Draw the reactance diagram. 2. Calculate the per unit impedances 3. If bms #1 is operating at 30 kV, find the current Assume base of 100 MVA, 300 kV on the generator side. Homework Equations P = VI s = p +jq...

Homework Statement Standing 20m away from a tower generating 2500W of power how much energy/s hits each of your eardrums? Surface area of eardrum=55mm^2 Assume that the speaker generates sound uniformly in a forward hemisphere. Homework Equations I=P/(4πr^2) r=20m P=2500W The Attempt at a...

Homework Statement If a stock has increased 400% over the last 6 years, then how much does it grow on average per year. Homework Equations 400 = 100(1+r/6)^6 The Attempt at a Solution Divide both sides by 100 4 = (1+(r/6)^6 Take the sixth root of each side. 1.26 = 1 + (r/6) Subtract...

Hi, I'm trying to prove something that I think is simple but am really struggling so would greatly appreciate any help! Over 2 weeks I receive rebates, the value of the rebate can vary both due to the rebate on each case and also the number of cases ordered. Between week 25 and week 26 my...

Hey guys I know that a laser can ionize air so that you could run current through air. I was wondering if anyone could tell me just how powerful (watts) the laser would have to be If I wanted to connect 2 point that are about 100 feet apart? 2 points have very low current but do have high...

I am trying to figure out what the total thermal energy emitted by completely transparent matter. It seems Planck's law can't do this because the thickness or geometry of the mass is not given, only it's surface area. The spectral radiance of a black body is given by Planck's law...

Homework Statement Ok so 1000(5.556 m/s – 0 m/s)/0.055 = 101018 Newton’s which is a unit of force. We know the force was applied for 1 foot of travel (.3048meters) Homework Equations So the incorrect conversion would be to multiply by .3048 to get 30790 Newton meters per second. I am missing...

Disclaimer: I've never had a chemistry class in my life. I'm reading a journal article that states the following: S2O32- + 2O2 + H2O → 2SO42- + 2H+ has the standard Gibbs energy of −766 kJ/mol at 25ºC. So, this is energy produced per moles of what?! Reactant? Product? If so, which reactant or...

Hello, I'm currently in college and getting a bachelors degree in physics and engineering, I also might get a bachelors in math too. I was wondering how much money I would start off getting with those degrees together? I've seen how much engineers get and physicist but what if you have both? Thanks

Hi I was working on delay-lines and I wanted to know if a pulse is delayed by 10 pulse lengths through a delay-lines than what is the corresponding storage bit for that delay line. Thanks

if I can move specific muscle in my toe via brain command, does this mean that in spinal cord there is a specific fiber that extends from brain to that toe? And let's say if in a lab rat we cut that single CNS fiber, the muscle affected will stop working without any other consequences to the...

Radiance is defined as radiant flux per solid angle per projected area normal to the beam direction: ##L = \frac{d^2 \Phi}{d \vec\omega \cdot d A_\perp}## where ##A_\perp = A \cos \theta## and ##\theta## is the angle between the beam direction ##\vec\omega## and the surface normal. I kind of...

Homework Statement Dry saturated steam at a temperature of 180ºC is to be produced in a fire tube boiler from cooling of 50000 kg/h of flue gases from a pressurised combustion process. The gases enter the tubes of the boiler at 1500ºC and leave at 100ºC. The feed water is externally preheated...

I keep track of how much time I spend doing intellectual labor. It works out to 60% of my free time and 49 hours per week. I also separate my labor into two categories: hard and easy. The hard category comes to 43 hours per week since last April. That includes computer coding and writing up...

Homework Statement Part A: Calculate how many mocules per cubic metre in air at 27°C and at a pressure of 1.1 atm (1atm is 1.01 x 10^5) Part B: What is mass in grams of 2.4m^3 of this air. Assume that 75% of the air is N2 (with molar mass of 28 g/mol) and 25% O2 (with molar mass of 32 g/mol)...

I've been grappling with this problem for a long time, but I think someone on this forum may know about this. Minimizing the joint number of products of a system of boolean equations is well-studied, and has various software implementations. Those are the Quine-McCluskey and Espresso...

Homework Statement A sample of a hydrocarbon is combusted completely in O2(g) to produce 19.65gCO2(g), 4.023gH2O(g), and 280kJ of heat. Calculate the value of ΔH∘f per empirical-formula unit of the hydrocarbon. Homework Equations None I know of The Attempt at a Solution Previous calculations...

Is there a formula covering this? (not including free fall/gravity) I have the drag coefficient, velocity and every other variable I think I would need for the object in particular.

A bicyclist applies varied force and velocity on their pedals as it goes around one revolution. The power distribution over one revolution is like two waves with the higher power being made on the downstrokes. The push through the bottom/top produces the lowest power. The question is does...

Homework Statement The distance between the both nucleons in the H2 molecule is 0.0741 nm The energy for the 3 lowest radiation levels of the molecule are: ##E_{0}=0 \\ E_{1}=0.0151 eV \\ E_{2}=0.0453 eV## How many revolutions per second does the molecule rotate with in the different states...

A couple of questions came up from different people and I thought I'd respond here in case anyone else might be wondering. First, not to confuse age of universe with Hubble time. Just coincidence that they are near. When you look at Jorrie's calculator (Lightcone link in my sig) you see we...

I have little to no experience with this area of physics, so don't assume I know certain things. A cone is spun (with the tip down) at a constant, not decreasing, RPM (Rotations per Minute). What is the minimum RPM for it to stay there without falling, and (if possible) the minimum RPM necessary...

Homework Statement the energy transferred per second by a progressive waves is directly propotional to the square of its amplitude, if two waves are in phase and superposed, the energy per second transferred by the resulatant wave propotional to A.) the sum of amplitude. B). The diffrenece of...

Homework Statement A mobile phone signal with a frequency of 1945Mhz is being broadcast from a transmitter with a peak output of 3kW. A: What part of the EM spectrum is the signal. Classify it in terms of its orientation of oscillation and propagation. B: Write a general equation for the...

Homework Statement The solar constant, the amount of solar energy reaching the Earth per unit time and area above the atmosphere and an element of area perpendicular to the direction from sunlight is 1.36 kW / m². For an element of area whose normal makes a angle q with the direction of...

Homework Statement Two tiny, spherical water drops, with identical charges of -1.00 x 1016 C, have a center-to-center separation of 1.00 cm.(a) What is the magnitude of the electrostatic force acting between them? (b) How many excess electrons are on each drop, giving it its charge...

Hi, I'm trying to find equation for an amount of solar energy that given place (of some latitude) on Earth's surface receives during a given day. I know it can be derived by using basic geometry, but I just need it for some application and don't want to waste time and risk mistakes. So if you...

say a car has 400 horsepower at the fly wheel with a V8. can you divide 400 by 8 to give 50 hp of power transmitted by each piston ? Just for a rough estimate, does it even come close to the real power transmitted by each piston or is way far off and wrong ? The reason why I think of this way...

Hi Could anyone explain to me the concept and significance of mesh density as a function of steps per wavelength? I am asking this in context of a frequency domain EM-solver. Thanks

1. estimate the fermi energy for lithium... the crystal structure of lithium is a bcc with a unit cell size of 3.5*10^-10 m [b]i need n, which equals N / V. if i divide by per atom, then i get (N/atom) / (V/atom) = valance / (V/atom). my question is how to get the volume per atom...

My problem is: A coffee house blended 18 pounds of espresso flavored coffee beans with 17 pounds of vanilla flavored coffee beans. The 35 pound mixture cost \$306.50. A second mixture included 19 pounds of espresso flavored coffee beans and 15 pounds of vanilla flavored coffee beans. The 34...

Homework Statement An economist has predicted that for the next 5 years, annual inflation will be 8%, and then there will be 5 years at a 6% inflation rate. This is equivalent to what average price change per year for the entire 10-year period? Homework Equations The Attempt at a Solution...

Hello guys, I was searching for what voltage does IEC standard call for Di electric test that should be done to low voltage panels? is it 2.5 KV for 1 minutes? If yes how how low voltage cable rated 600/1000 V can withstand 2.5KV without insulation failure?

I am wanting to calculate the theoretical packs per minute of a machine. The machine pushes packs into a indexing conveyor and is transported along the conveyor and is cross pushed on to an exit conveyor. Each pack is 144 mm long and the machine indexes every 0.65s plus a 1.4 second dwell for...

I an ideal gas how do I calculate the number of collision per unit area? By collision I do not mean collision between the atoms but rather it is a problem where I know that a nucleation cluster of area A is in my gas, and I want to find the probability that it will get hit by an atom. I know the...

Homework Statement For nickel, which has an atomic magnetic moment of 0.61 and an atomic weight of 58.7, calculate the magnetic moment per kilogram of the material Homework Equations None given The Attempt at a Solution Do I not need density to use formula for saturation...

Homework Statement Your roommate is an aspiring novelist and asks your opinion on a matter of physics. The novel's central character is kept awake at night by a leaky faucet. The sink is 19.6cm below the faucet. At the instant one drop leaves the faucet, another strikes the sink below and...

Homework Statement You are consulting for an amusement park that wants to build a new "Rotor" ride. In order to increase capacity, they would like to build a unit with a 14.2-ft diameter. The Rotor should provide a centripetal acceleration of 3g. What must be the angular speed in revolutions...

Homework Statement Given a photon polarization state lphi> = lx> 3/5 + ly> 4i/5 , a beam of photons transmit N photons per second in such a state. An L-polarized photon has an angular momentum hbar along its direction of motion, and an R-polarized photon has an angular momentum of the same...

A trivial question. I know that current is the amount of charge passing per unit time across a area. And Potential difference is change in potential or change in potential energy per unit charge or work done per unit charge. And also from Ohms law, V is directly proportional to I. So...

A Ladder $13ft$ long is leaning against the side of a building. If the foot of the ladder is pulled away from the building at a constant rate of $\displaystyle \frac{2 in}{sec}$ how fast is the angle formed by the ladder and the ground changing in $\displaystyle\frac {rad}{sec}$ at the instant...

the rides on a carousel are represented by $2$ circles with the same center with $\displaystyle\omega=\frac{2.4 \text {rev}}{\text {min}}$ and the radius are: $r_{13}=13 \text{ ft} 11 \text { in}= 167 \text { in}$ $r_{19}=19 \text{ ft} 3 \text { in}= 231 \text { in}$ find...