Per Definition and 545 Threads

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...

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...

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...

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...

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.

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?

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...

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

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...

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...

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...

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...

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...

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 -...

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...

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 =...

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...

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...

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?

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...

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...

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...

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...

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 =...

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?

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...

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 :-)

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...

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...

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...

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.

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...

Homework Statement A packed bundle of 100 long, straight, insulated wires forms a cylinder of radius R = 0.600 cm. If each wire carries 4.50 A, what are the magnitude and direction of the magnetic force per unit length acting on a wire located 0.200 cm from the center of the bundle?Homework...

Homework Statement Basically, the problem states that a cavity at temperature T is emitting EM waves isotropically in all directions (with frequency distribution of Planck's Law). If the time averaged density is <e>, find the value of d<S>/dw where w is the solid angle and the quantity is the...

Is Molarity simply "moles per liter" Is Molarity simply "moles per liter"

Homework Statement A boy whirls a ball on a string in a horizontal circle of radius 1.0 m. How many revolutions per minute must the ball make if its acceleration towards the center of the circle is to have the same magnitude as the acceleration due to gravity? Homework Equations a=v^2/R...

"flux per unit projected area per unit solid angle," L = \frac{\partial \Phi}{\partial \left(cos \Theta \right) \ \partial \Omega} What is this quantity? I mean, I know it's "flux per unit projected area per unit solid angle," how does the math work? I know it's not \frac{\partial...

GRB's occur once per day. over 10 billion years that's 3650 billion bursts (in the observable universe?). I think there are said to be around 100 billion galaxies in the observable universe so does that mean that 36 bursts occur in each galaxy...

Homework Statement Some electrical appliances are used with long cables to connect to them to the electrical supply. State and explain 2 reasons why these cables should have a low resistance per unit length. The Attempt at a Solution well for the long cables, a low resistance per...

Find the capacitance per length of a co-axial cable with a conductor of radius a and a thin shield of radius b.

Many derivations of mercury precession angle per orbit \Delta\Phi, equate this to extra angle per orbit \delta in excess of 2\pi that is \delta = \Delta\Phi But I am getting this relation \sqrt{4\pi\delta}= \Delta\Phi from arc length of helix and circular orbit. What am I doing...

Hello. I'm trying to find the individual contributions of carbon atoms to the charge carriers in graphene. In other words, I'm trying to answer "How many charge carriers does one carbon atom supply?" Here is what I've done so far: Taking the max. carrier density as 10^13 1/cm^2 and the...

My physics professor posed that question to us a while back, and he never gave us the answer. I tried solving it but I had no idea what units to convert it too. Does anyone have any ideas as to what the answer may possibly be?

Considering momentum to be in units of \rm kg^1 m^1 s^{-1}, is there any particular attribute associated with \rm kg^1 s^{-1} (other than "momentum per metre")? Or perhaps the inverse \rm s^{1} kg^{-1}? Just curious.

Hi. How do you convert watts per metre squared to decibels? I know you use logs but can't seems to work it out. Thanks for any help.

a) Calculate the average binding energy per nucleon in the deuterium nucleus. b) The energy that binds an orbiting electron to the hydrogen nucleus is 13.4 eV. Calculate the ratio of the binding energy per nucleon to the binding per electron in deuterium. Which particle is held more tightly...

why is it the maximum electrons per shell is 2,8,18,32,50 ... Wouldn't 2,8,16,32,50 make more sense mathematically? Are there any equations the show why this occurs?

[SOLVED] Finding mass per unit length for stretched strng given tension? A transverse wave on a stretched string under Tension = 5N is defined by the equation: y(x,t) = 0.1cos(2pi/5(x - 10t) Find: a) amplitude = 0.1 m b) wavelength = 0.4 m c) angular frequency = 4 rad/s d)...

Hi, I have a question asking me to find the number of photons emmitted per second. I am given the information that the Gallium Arsenide diode laser emit 0.9 mW of power inside a CD player. The bandgap of the Gallium Arsenide is 1.42 eV. What equation is used to find this?

If you stretch a wire, increasing its length will the number of electrons per cubic metre decrease? Assuming the Cross sectional area stays the same. The number of electrons will surely stay the same, and won't increase just by you stretching it, and the number of cubic metres has increased, so...