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. B

    Distance formula and addition of meters per s

    Hello guys. I have issues understanding a rather simple physics concept and I hope you can help me out. I've tried asking help from several people, but nobody was able to isolate the problem. For constant acceleration, it is said that d=(Vi+Vf)/2*t. d being distance, Vi is initial velocity...
  2. edpell

    When do we run out of uranium? How much is used per year?

    When do we run out of uranium? How much is used per year? How much is in stock piles? How much is in deposits that we can afford to extract?
  3. Monocerotis

    Calculating Power Usage for Devices

    Homework Statement The question asks for us to go around our house, figure out the power usage of different devices, based on the estimated time use of these devices and calculate the total power usage per month. Homework Equations Energy = Power X Time Power = kW Time = hours...
  4. C

    Determine the mass per unit length of the string.

    Homework Statement A guitar's E-string has length 65 cm and is stretched to a tension of 85 N. It vibrates at a fundamental frequency of 329.79 Hz. Determine the mass per unit length of the string. 1Your answer is in kg/m Homework Equations (mass per unit length) = (tension) /...
  5. B

    7 TeV per beam compared to 1 TeV per beam

    If I've read this correctly, it seems the LHC will be colliding beams at 7 TeV each, producing a total collision energy of 14 TeV. The previous record was approximately 950 GeV at LEP/Tevatron producing a total collision energy of 1900 TeV. When the LHC starts colliding early next year (perhaps...
  6. R

    Point source (radioactive)that emits 100 gamma per second

    Hi all, i have a critical question. You have a point source (radioactive)..that emits 100 gamma per second. Now if you place a metal or foil (e.g., Al)..will the no. of gamma reduces? If it reduces how to calculate..based on beer law..(if we know the attenuation coefficient of that metal and...
  7. M

    Particle Accelerators: How do I calculate the amount of particles per bunch?

    Homework Statement The circumference of the collider is 26.66 km, and there are 4 equally spaced points where the beams collide. A collision takes place every 22microseconds at each one of the collision points, with 4 bunches in each beam. The average current per beam is 3mA. I...
  8. N

    Binding energy per nucleon / fission / fusion

    What I'm looking to understand is why fission and or fusion result in the release of energy. I understand that: By looking at the Binding Energy per Nucleon Curve, due to the strong force acting at very small length scales and falling off as 1/x^3 and the electro-magnetic repulsion of the...
  9. C

    Find its angular acceleration in radians per second per second

    A potter's wheel moves uniformly from rest to an angular speed of 0.23 rev/s in 29 s.
  10. N

    Binding Energy per Nucleon (Fission)

    Homework Statement By analyzing the Binding Energy per Nucleon Curve, and using the equivalence factor 1amu=931.4 MeV, show that a U fission frees energy equivalent to 0.2 AMU. Homework Equations E=mc^2 A fission I picked: U-235 + slow neutron ---> 141/56 Ba + 93/36 Kr + 2n...
  11. M

    Force per unit length on the wire in the bottom left hand corner.

    1. Homework Statement [/b] Suppose in the figure that the four identical currents i = 13 A, into or out of the page as shown, form a square of side 64 cm. What is the force per unit length (magnitude and direction) on the wire in the bottom left hand corner? (N/m) Take the positive y direction...
  12. T

    Finding capacitance per unit length

    Homework Statement You are planning to install a home video studio. A very important piece of information is missing from the specifications. You must find the capacitance per unit length for a coaxial cable. The cable has an inner radius of 2.0mm and an outer conductor 4.0mm in radius...
  13. M

    How many rotations of peddels per second?

    Homework Statement A bicycle drives on a straight road with a velocity v = 18 km/h. How many turns (rotations) of peddles per second must be carried out by cyclists, if the radius of the wheels r = 35 cm, and the ratio of the radii of front and rear gear wheels is 2:1? Homework Equations I...
  14. T

    Electron repulsion per unit volume

    Hi, I am trying to calculate how many electrons I need to confine in one cubic centimeter to make the pressure on the "walls" 1psi. I've tried the equation for the repulsion of two charges, but we're talking about trillions of electrons here and they're all pushing on each other however...
  15. V

    Young's Modulus / Force per Area Ques.

    Hello, My question in this. If you have a system where two rods (different moduli of elasticity and different cross sectional areas, but equal in length) are compressed uniformally by a load, how do you calculate the compressive deformation in the rods. The compression of both will be...
  16. M

    How to calculate tire rotation per sec/min/hour

    Hello, Can someone help me with a formula for calculating a tire revolution per sec/min/hour taking as reference the air valve? The variables are tire size and speed in km/h. Thank you anticipated.
  17. B

    Capacitance per unit length help

    1. Homework Statement [/b] You are planning to install a home video studio. A very important piece of information is missing from the specifications. You must find the capacitance per unit length for a coaxial cable. The cable has an inner radius of 1.1 {\rm mm} and an outer conductor 3.1 {\rm...
  18. H

    How do I calculate Volts per cm (V/cm) with the following given?

    Homework Statement How do I calculate Volts per cm (V/cm) with the following given? Two coaxial tubes with 20kV placed across them. Inner tube (actutally solid rod) has an OD of .5" and a length of 4" Outer tube has an OD of 1.00" and a length of 4" Homework Equations The...
  19. C

    Finding revolutions per minute

    Homework Statement An astronaut is rotated in a centrifuge of radius 4.0 m. Homework Equations v = omega * radius a = v^2/radius The Attempt at a Solution Ok, so I first found the omega for this acceleration, which came out to be omega = 3.56179 s^-1 then I decided...
  20. C

    Conduction, How much heat flows through per second?

    An iron pot filled with boiling water is on top of a stove. The bottom has a surface area of 200 cm2 and a thickness of 2.00 mm. If the bottom has a temperature of 480°C, how much heat flows through it per second? Answer wanted in kJ/s Q/t= (kt)A*(deltaT/d) The thermal conductivity...
  21. B

    The 29.97 frames per NTSC standard

    I have read before that when color television was developed the frame rate was changed from 30 frames per second to 29.97 frames per second to avoid some kind of problem with the circuitry, but I have never seen an explanation of just what this technical problem was. My somewhat educated guess...
  22. V

    Absorption coefficient per unit path length determined for excitation

    How is the absorption coefficient per unit path length determined for excitation sites in a host crystal with an excitation site density of N and a bandgap of the excitation site equal to the photon energy? What I am trying to determine is how many photons will be absorbed for a given length.
  23. E

    How many hours per week for Waves & Oscillations?

    I'm budgeting my time for the upcoming semester, and I've made a goal with myself to spend at the bare minimum 8 hours per week for an undergraduate course in Waves + Oscillations - with a surplus of 14 hours for a week that has an exam in it. Does this seem like a reasonable amount of time?
  24. T

    Transformer and Generator in Per Unit System

    Homework Statement A 3-phase generator rated 100 MVA, 13.2 kV, X = 20% is connected through a Δ/Y transformer to a transmission line whose series reactance is 40 ohms per phase. Assume that the base values in the line circuit are 200 MVA and 115 kV. Find the generator and transformer...
  25. E

    Calculating Visible Light Photons Emitted Per Second & Distance

    a.) If the average frequency emitted by a 200 W light bulb is 5x10^14, and 10.0% of the input power is emitted as visible light, approximately how many visible-light photons are emitted per second? I solved this part of the problem by finding the energy (E = hf) and dividing 10% of 200W by...
  26. G

    Classification of Engineering drawings as per Standards

    Hello, What is Level 1 engineering drawing? What does it mean? Is there any particular section dealing about classification of engineering drawings in ASME Y 14 series. Please throw some light on this Thanks
  27. M

    Credits per semester and GPA distribution

    I have two questions: 1. What is the average number of credits one takes per semester in Grad school in the US? To be more precise: how many courses does one usually take per semester and how many hours of lectures/tutorials does it correspond to weekly? 2. What is the distribution of grades in...
  28. M

    Find the magnitude of force per unit length exerted by one wire on the other

    Homework Statement Two long straight wires in the xy plane are parallel to the x axis. One wire is at y = −8 cm and the other wire is at y = 8 cm. The current in each wire is 24 A and the currents are in the negative x direction. The permeability of free space is 4 π × 10−7 T · m/A...
  29. M

    G-Force Accelerometer conversion to Pounds per Square Inch

    So, the title says it all. background info on this question. I purchased a Herman Digital Trainer. It measure the impact of punches and kicks based on G-Forces. I was wondering if it was possible to a G-Force reading into Pounds per square inch reading. This is the websites description...
  30. F

    Finding Revolutions per Second of Electron & Proton in Magnetic Field

    Homework Statement An electron of speed v enters a region of magnetic field B directed normally to its velocity and is deflected into a circular path. Find an expression for the number of revolutions per second the electron will make. If the electron is replaced by a proton, how does your...
  31. H

    How Many Meters Does a Car Travel to Reach 125 km/h from a Standstill?

    Hi All, I am new here and trying to solve a simple problem. If a car can go from 0-100 in 7.4 sec, how many meters will it take to reach 125 meters? Do I need more information to work this out? If someone could help me solve this it would be appreciated as I am trying to get my head...
  32. R

    Find the amount of energy per gram in various types of nuts

    Homework Statement We lit the nuts on fire and used them to heat up the water which was in an aluminum can. We then recorded the temperate. How would I find the energy? an example of the results would be cashew mass of nut before- 1.53g temp of water before-23C mass of nut after -...
  33. S

    Diffraction grating, lines per mm, and how to show the spacing

    A diffraction grating is labelled 300 lines mm^-1 (lines per mm) Show that the spacing (d) between the lines on the grating is 3.3 x 10^-6m i can't really think of any relevant equations. but I'm assuming standard form. i can't believe that the answer would be as simple as converting to...
  34. X

    Energy per unit area of EM wave

    Homework Statement The E field in an EM wave has a peak of 22.8 mV/m. What is the average rate at which this wave carries energy across unit area per unit time? Homework Equations S = e_0*c*E^2 The Attempt at a Solution where e_0 = 8.85*10^-12 c = 3*10^8 E = 0.0228 V/m S =...
  35. C

    Watts=Newton-meters per second

    I've got to ask because I know my students will ask (they have a game where they try to stump the teacher with physics questions.) A Watt is equal to a Newton-meter per second, which is to say the amount of work done per second. Work is the amount of force applied for a distance. Ok, so a...
  36. M

    Slits per cm on diffraction grating

    Homework Statement Light of 650 nm can be seen in three orders in a particular grating. About how many slits per cm does this grating have? Homework Equations Yikes. The Attempt at a Solution Either this question is ridiculously hard resulting in me not even having a clue...
  37. S

    Is it worth going into $25k debt per year to go to Michigan Engineering?

    My parents are willing to pay $25,000 of my tuition and I will have to take out loans on the rest of my expenses. Should I do this to go to the superior school or go to a state school like UVA or VT which my parents would pay everything for?
  38. M

    Protons delivered per second in a proton beam

    Homework Statement a 5.0 mm-diameter proton beam carries a total current of 1.5mA. the current density in the proton beam, which increases with distance from the center, is given by j=j(edge)(r/R), where R is the radius of the beam and j(edge) is the current density at the edge. a) how many...
  39. W

    Finding mass per unit length of a string

    i am a non physics or math major taking a 'physics of sound and music' course that deals with different wave forms. i am enjoying the class very much (more than i thought i would!) but am having trouble with the math, as the last math class i took was pre-calculus my junior year of high school...
  40. B

    Calculating watts per square foot

    I am working on a project to consider how much air conditioning in a metropolitan area raises the temperature outside. I am trying to figure out how to translate the temperature outdoors (say 32 degrees C) into watts per square foot. Once I have the watts per square foot of heat already in the...
  41. X

    A very long uniform line of charge has a charge per unit length of 4.82 uC/m

    Homework Statement A very long uniform line of charge has charge per unit length 4.82 uC/m and lies along the x-axis. A second long uniform line of charge has charge per unit length -2.46 uC/m and is parallel to the x-axis at y1= 0.418 1-)What is the magnitude of the net electric field at...
  42. F

    Circluar Motion Involving Rotations Per Minute

    Homework Statement What is the magnitude of the acceleration of a speck of clay on the edge of a potter's wheel turning at 40 rpm (revolutions per minute) if the wheel's diameter is 35 cm? Homework Equations v=2(pi)(r)/t a=(v^2)/r The Attempt at a Solution 2(3.14)(.175)/.67 =...
  43. A

    GM Crops vs Organic Farming: Output Per Acre Comparison

    How do GM crops (both current and potential in the near future) compare with organic in terms of output per acre? How does it compete with such methods as Fukuoka Natural Farming, and other forms of permaculture?
  44. C

    Calculating Energy Received by a Human Eardrum at Threshold of Hearing

    Homework Statement The radius of a typical human eardrum is about 4.10 mm. Calculate the energy per second received by an eardrum when it listens to sound that is at the threshold of hearing, assumed to be 1.04E-12 W/m^2. Homework Equations I=P/A The Attempt at a Solution First i...
  45. S

    Why is the speed of light exactly exactly 299 792 458 meters per second ?

    Is there any published theory that explain and proves why the speed of light is exactly 299 792 458 merters per second ? I do not know of any ! Do you ? Best regards Me :-)
  46. H

    Moment of Inertia for Infinite Density (mass per area)

    Homework Statement Suppose you have the density of a disk given by σ=σ0*rn. For n approaches infinity, find the limit of M.I. Interpret your result, which should be physical, reasonable and intuitively clear. Homework Equations Now i found the moment of intertia of the object to be...
  47. S

    Photons per second hitting an aperture

    Homework Statement >An aperture is 3m away from a light bulb, with an area of .09m^2. >The light bulb is 100 Watts, and 2.5% of the energy is converted to visible light > From the previous part: The average wavelength of the light is 520 nm, meaning that each photon has an energy of 2.386 eV...
  48. A

    Inductance and Capacitance per Temperature

    I am studying the relationship between transmission speed in a Transmission Cable and the temperature of the cable. This speed is given by (as per discussion in the Feynman lectures) v=\frac{1}{\sqrt{LC}} where L is the inductance per unit length C is the capacitance per unit length...
  49. wolram

    Why Are Traffic Cones Frequently Present on Motorways with No Apparent Activity?

    Is there some statistic that gives a ball park figure? And doe's anyone knows why they are even there, time after time i see these cones but no activity.
  50. R

    Finding turns per meter in a solenoid

    Homework Statement The magnetic field produced by the solenoid in a magnetic resonance imaging (MRI) system designed for measurements on whole human bodies has a field strength of 4.0 T, and the current in the solenoid is 300 A. What is the number of turns per meter of length of the...
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