# What is Per: Definition and 565 Discussions

PeR (Please Explain the Rhythm) is a Latvian pop and beatboxing band formed in 2007. The original line-up was Ralfs Eilands, Emīls Vegners, and Pēteris Upenieks. Vegners left the band in 2007 and was replaced by Edmunds Rasmanis. But when Upelnieks left the trio in 2011, he was not replaced, rendering the band a duo consisting of just Eilands and Rasmanis. After three failed attempts in earlier years to represent Latvia in the Eurovision Song Contest, PeR won the 2013 Dziesma contest and represented the country in the 2013 Contest with the song "Here We Go" and placed last in the second semi-final.

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1. ### Three Phase Per Unit System - Mark up, represent as single phase equiv

I'm seeking some reassurance I've understood the question since there are no answers given in the book and I'm getting a bit tied up in knots. What I am struggling with most is there are three per unit values for impedance already noted on the diagram without qualifying what ##Z{base}## is or...
2. ### How many kilocalories per gram are there in a 5.00-g peanut?

For this, The solution is, However, I am not sure why they did part(a) like that. I thought we would do it like this: ##Q_{nut} + Q_{w} = 0## since calorimeter is ideal so energy is conserved in the nut-water system ##Q_{nut} =-Q_{w}## ##Q_{nut} = -(0.500)(4184)(54.9) = -1.15 \times 10^5 J##...
3. ### I Feynman's QED; 36,000 revolutions per inch for red light.

In Feynman's book, QED, The Strange Theory of Light and Matter, page 27 he says, "As long as the photon moves, the stopwatch hand turns (about 36,000 times per inch for red light); when the photon end up at the photomultiplier, we stop the watch." I've been puzzling about the significance of...
4. ### A Nutation calculation per Meeus: unsure how to proceed

In Astronomical Algorithms, Meeus gives a table for periodic terms for nutation in longitude (Δψ) and obliquity (Δε) according to the 1980 IAU Theory of Nutation. I'm unclear how the table should be used. Do I: Use each row to generate the argument of trig functions, presuming D, M, M', F and Ω...
5. ### Work per particle of a NaCl chain

The problem states to find the work per particle to assemble the following NaCl chain. I just want to post my work here to verify I have the correct answer. My work is attached in the image provided.
6. ### How many items does Amazon need to sell per day to justify market cap?

I'm perhaps not so interested in the "correct" answer but rather whether the methodology is valid. Let's say Amazon's market cap is ##\sim $2 \mathrm{T}##. The average item ordered off of Amazon is ##\sim$20##, and since they're about high-volumes & low-margins an estimate for the gross profit...
7. ### The binding energy per nucleon of tritium

Hi, I know from conservation of energy that ##E_i = E_f## Thus, ## M_h c^2 + binding energy = M_{he}c^2+ M_e c^2 + K = M_{he}c^2 + 0.5 MeV + 0.0186 MeV## If I'm right I have to find ##M_{he}c^2##, but something is missing in my understanding, since I don't see how to find that mass energy...
8. ### How to wind a brushless motor (number of windings per stator)

Hi folks, I'm searching for information/procedure and also calculations/equations on how to correctly wind a stator on a (general or DC 3-phase) brushless motor? I.e. how to wind a copper wire X number of times around the stators, and thus get the desired performance/force that is required...
9. ### Yr 10 Combinatorics -- Rearranging the letters of ABRACADABRA per this rule....

Hi everyone Can anyone help with this combinatorics problem? I have the answers, but don't understand how the answer was derived. Here's my attempt and reasoning. Step 1: Determine all possible combinations Since A, B and R have multiple letters, the number of possible combinations is given...
10. ### MHB 1.2.1 propelled vertically upward with an initial velocity of 20 meters per second.

$\tiny{1.2.1}$ An object is propelled vertically upward with an initial velocity of 20 meters per second. The distance s (in meters) of the object from the ground after t seconds is $s=-4.9t^2+20t$ (a) When will the object be 15 meters above the ground? $15=-4.9t^2+20 \implies -4.9t^2 =-5$ ok...
11. N

### How Do You Calculate Revenue Per Share Using the Midpoint Formula?

The revenue per share for Twitter, Inc. was $1.17 in 2013 and$3.25 in 2015. Use the Midpoint Formula to estimate the revenue per share in 2014. Assume that the revenue per share followed a linear pattern. (Source: Twitter, Inc.) This is an exercise using the midpoint formula. I just want to...
12. ### I Amount of Noise extinction in Acrylic glass per thickness in mm

Hey guys, I need your help with the following topic on which I couldn't find sufficient information on the internet to solve. In the need to further insulate my velux roof swing window against against airborne motor and tire sound from the nearby street, I came across the idea to install an...
13. ### Binding energy per nucleon of the nucleus

How exactly would it then be calculated? Here's what I have tried: proton mass: 1.007276 amu Neutron mass: 1.008665 amu Sulphur-34 mass: 33.9678668 amu Calculation: 1.##(16\cdot1.007276)+(18\cdot1.008665)+(16 \cdot0.000549)=34.28117## 2.##34.28117-33.9678668=0.3133032## 3. 1 atomic mass...
14. ### Medical Minimum amount of sleep per night for 4 months

I am a 17 year old male with no major health conditions. I want to know if there will be any long term effects of less sleep(and practically no sleep schedule) ranging from anywhere between 4-5 hours a night(sprinkled with occasional all-nighters) for a period of 4-5 months. a quick google...
15. ### Calculate change in entropy per minute.

So what I did was find the change in Q per min. Mass melted per min * latent heat capacity = Q per min = 11.5 kg /min * 3.4*10^5 J/kg = 3910000 J/min Now the equilibrium temperature is 100 degrees Celsius or 373.15 degrees kelvin. If I do 3910000 J/min / 373.15 K I get 10478 J/(K*min). This...
16. ### Kilojoules per kilo to watts per second

My understanding is that electrical devices are rated in watts which is really watts per second. For instance if a peltier module is rated at 5 watts it will use 5 watts per second. I had thought that it should be simple to convert kilojoules to watts but everywhere I’ve looked i can only find...
17. ### What is the leakage rate of my underground piping system?

This is a situation I don't often deal with; I have an underground piping system that is failing a pressure test and losing pressure at a rate of about 1psi/min from 80psi. I'd like to calculate the leakage rate. The pipe is a simple 10" diameter, schedule 40 steel pipe, 500' long (0.365"...
18. ### I Source of Gravity of heavy mass as per GTR

Regarding the equivalence principle of GTR, inertial mass and heavy mass are comparable, and are causing identically effects on mass objects. The pseudo force of inertial mass could be experienced in an accelerated frame of reference. In that point the "Force" appers, while energy is...
19. ### Decrease of Solar radius per year using Virial Theorem

Hello, I am trying to solve this question: Assume that the Sun's energy production doesn't happen by fusion processes, but is caused by a slow compression and that the radiated energy can be described by the Virial Theorem: $$L_G = - \frac{1}{2} \frac{GM^2}{R^2} \frac{dR}{dt}$$ How much must...
20. ### MHB -act.63 cost per game with season pass

Armin is trying to decide whether to buy a season pass to his college basketball team's 20 home games this season. The cost of an individual ticket is \$14, and the cost of a season pass is \$175. The season pass will admit Armin to any home basketball game at no additional cost. What is the...
21. ### Mass of vapor per hour for heating water

I thought about using Black principle to solve this question but I am confused about the final temperature of system Q released by vapor = Q absorbed by water mvapor . cvapor . ΔTvapor + mvapor.Lv + mvapor . cwater . ΔT2 = mwater . cwater . ΔTwater But what is the final temperature of the...
22. ### I Decomposition per the Fundamental Theorem of Finite Abelian Groups

According to the book I am using, one can decompose a finite abelian group uniquely as a direct sum of cyclic groups with prime power orders. Uniquely meaning that the structures in the group somehow force you to one particular decomposition for any given group. Unfortunately, the book gives no...
23. ### Calculating Discharge Rate of Fluid in Circular Area

This is actually right at the start of another derivation, but I can't understand how the author gets the formula for ##q##. So the discharge per unit thickness is the circumference of the circle, multiplied by the velocity at that point (at ##r##)? I thought the formula for flow rate was...
24. ### Is Bernoulli's Theorem an Expression of Energy Density in Fluids?

As summarized.
25. ### I Converting "Luminosity per unit wavelength" to "Luminosity per unit frequency"

If there is a luminosity per unit wavelength defined as L_λ dλ, am I correct in thinking that the conversion to luminosity per unit frequency (L_ν) would be L_ν = L_λ (λ^2/c)? And building off of that, if the shape of a spectrum was proportional to a power-law: L_λ = λ^(β), is there a way to...
26. ### ADM formulation Initial Value Problem data per spacepoint

I'm having a bit of trouble getting a clear picture of what is going on here, so if anyone can shed any light, it will be greatly appreciated. 1. I can see how the metric coefficients provide the six numbers per spacepoint, but it can't always be possible to transform the metric into a diagonal...
27. ### Finding the excess electrons per lead atom

a. This is easy with ## q = n*e ## ## 3.2 * 10^{-9} = n * 1.6*10^{-19} ## ## n = 2*10^{10} ## electrons b. Total Lead atoms are ## \frac {8 * 6.022*10^{23}} {207} = 2.3 *10^{22} ## I used the Avogadro number. Total electrons = ## 2.3 * 10^{22} * 82 = 1.88 * 10^{20} ##, here i multiplied with...
28. ### What will be the number of collision per second in a unit area?

By using PV=nRT formula, I have found the volume of the vessel. As far as I have learned to calculate the number of collision in a unit volume. So, it is being difficult for me to find the right way to solve. I searched on the internet and have got this...
29. ### What does "....10000 units per 15 min (quick reduction)" mean?

Hello, looking to find out what the term "10000 units per 15 min (quick reduction)" from the WHO means in terms of using heat to kill a virus.
30. ### I EV per Torr*cm -- What does it mean?

I was reading about this https://en.wikipedia.org/wiki/Nitrogen_laser and it says "80 to 100 eV per Torr*cm pressure of nitrogen gas". I'm finding this a little bit confusing. It needs some specific amount of energy in a centimeter of volume with 1 Torr of pressure?
31. ### Finding the magnitude of the hydrostatic force per unit of circumference

Hello all I am trying to find the hydrostatic force of a cylindrical tank of water. I was hoping someone could help point me in the right direction. I have a cylindrical water tank. The dimensions are as follows:- I need to find the magnitude of the hydro static force per unit of...
32. ### Correct statement regarding the graph of binding energy per nucleon

Option A is correct because the graph increases sharply at lower nucleon number Option B is correct because higher binding energy per nucleon means more stable Option C is correct because either fusion or fission will bring the product to Q So my guess the answer is D but I do not understand...
33. ### Find the force acting per unit width on the vertical wall

A container of height 3m and width 5m is filled with water upto 2 m. It is accelerated such that the water is at the brim (it is about to spill). When it moves with this acceleration find the force acting per unit width on the vertical wall. I found the acceleration for the condition provided...
34. ### When did "eight hours of sleep per day" become an accepted guideline?

When was the notion that most people need eight hours of sleep per day popularized? Was it a rule of thumb before there was any scientific research to support it? Did the notion arise after the widespread use of electric lighting - when people acquired an alternative to going to sleep when...
35. ### Other Help finding GR and PER grad school programs?

Hi Folks, I am finishing up my last year in undergrad (physics with a math minor) and am searching for potential grad schools. My areas of interest are pretty much exclusively in Gravitation (specially theoretical study of general relativity) and Physics Education Research, with a bit of...
36. ### Power developed by a person on eating 100g of ice per minute is?

P=W/t W=Q= mL = (100x 80x 4.2)/1000 (kg x J/kg) = 33.6 t= 1 minute= 60s P= 33.6/60= 0.56 watt... but the answer provided is 560J/s...?
37. ### How are counts per frame calculated in CCD for spectrometry?

I don't know if this is the appropriate forum for it. But I'd like to understand the concept of counts per frame in CCD in visible or IR spectrometry. If the exposure is say 200 ms and there are 12 frames. What is the counts per frame? Do you multiply 200ms by 12 frames to come up with 2400...
38. ### B Photons as bullets at 10 trillion FPS (frames per second)

The following extraordinary experiment from Caltech highlights the 'classical' behaviour of light(photons) traveling through medium. It vindicates the notion that photons(at least from our limiting human perspective) do behave the same way as other quanta(much like ordinary 'matter' - chairs...
39. ### How many alleles per gene the human species have today?

Hello. Yesterday I was making some calculations, and I started to wonder the average number of alleles per gene the human specie have today. The best question would be how many mutations per base or how many alleles in an average 1000 base gene, as genes vary in size. What made me wonder this...
40. ### MHB What is the average profit on producing and selling 40 items per day

business has an average cost of AC(x)= 100x+2x/x and its average revene per day is AR(x)= 100x+3/x what is the average profit on producing and selling 40 items per day how many must we sell to get an average daily of \$80?

42. ### Heat transfer to solution per litre

Problem Statement: This is a question I made up to understand more about the calorimetric power. The equation below is given by Koda et. al (2003). A saucepan of water (400 mL) on a stove is been heated at constant temperature. The calorimetric power can be written:##Power(W)= (\frac{dT}{dt})...
43. ### Is the blood supply distinctive or collateral per organ?

Hello! Is the blood supply to an organ done exclusively by one (or more) distinct arteries or there is extensive collateral supply from different arteries? For example, is lungs' circulation only from bronchial and pulmonary arteries/veins or there is collateral blood circulation as well from...
44. ### B The difference in the binding energy per nucleon

if binding energy per nucleon is proportional to the number of nucleons in the range of the nuclear force. then why is the binding energy for carbon 12 higher than nitrogen 14
45. ### Convert solar radiation from Joule per cm square to Watt per meter^2?

I have solar radiation data in the units of Joule per cm^2 (joule per square centimeter) measured hourly. I want to use this data in evapotranspiratin calculation which requires radiation units as Watt per meter squared. How can I do this conversion?
46. ### How to convert Insulation Loss (in Watts/meter) to kWh energy savings per year?

Hi, I'm working for a company that want me to calculate something for them. I haven't done physics since A level so have forgotten a lot of it and am now very stuck! They want to know the kWh per year they will be saving by reducing their heat loss (which they have given me in watts per meter)...
47. ### How many times per minute does an object pass equilibrium? (Diff Eqs)

Essentially, my question boils down to just part b. My initial thoughts on how to solve this are illustrated above in the second image. To me, I had just interpreted omega, the frequency, as cycles per second. From there, I simply multiplied to get it into minutes. After discussing with a prof...
48. ### Atmospheric pressure per square cm

Hi, I have a problem to understand one small thing. They say that air pressure per square cm at sea level is approximately 1 kg. So at 2 sq cm it will be 2 kg, at 3 sq cm it will be 3 kg etc. But... Here where I have a problem. The thing is that inside 2 square cm you can put 4 one square cm...
49. ### I Help - pixels per inch paradox

Hello, I could some help. I've reached some sort of paradox. Ultimately I'm trying to calculate the number of pixels per inch, given a pixel size of 5177 nm and extended at a distance of .7inch (.0178 meters) (A) (60 arcsecs * 0.0178 meters)/206268 = 5177nm pixel per arcmin (B) 5177 * 60 =...
50. ### A How to choose the number of particles per site in Fermionic DMRG?

I am doing DMRG (in traditional formalism, not MPS) for Hubbard model H = -t ∑i ∑σci,σ ci+1,σ + U∑ini,σni,σ- In every iteration we add two sites to the system, but how do we set that how many particles are allowed in the system?