Units Definition and 975 Threads

My intuition is that it would be unitless. But if it's magnitude squared is a probability density, then its units would have to be 1 over some power of length. Specifically 1/L^(n/2) where n is the dimension. Where's the error in my thought? Thanks

I am new to the forum, and I am sure it will be evident by this first question, but I hope to learn a lot here. so.. here is what I was thinking about that prompted me to look for a math forum. Say I have (20cm)2. That would be 400 square centimeters, or, 4 square meters? Now, what if I...

for the frequency of revolution of electrons, the unit is expressed as rev/s but for the frequency of a photon, the unit is hz my question: can rev/s also equal hz?

A nice tutorial by E.J. ROSCHKE PROPULSION DIVISION JET PROPULSION LABORATORY, Caltech. http://www.its.caltech.edu/~culick/Roschke.pdf

I have been reading http://en.wikipedia.org/wiki/Planck_units Why do they use Newton's universal gravitational constant, when that is a low gravity approximation and general relativity is what it used to work things out?

I'm told the spectral radiance of a source is in the following units W ---------------- cm^2 * sr * nm And I try to use this to figure the spectral output of monochromator (in W), but I can't seem to cancel out the units. I multiply the spectral radiance by four other terms...

how do you change the measurement unit for an electron mass from kg to MeV/c^2?

Hi, I have to find the units of Z[x]. I am little unclear and my book does not go into detail. Does U(Z[x]) mean I need to find every polynomial with integer cooefficients that has a multiplicative inverse? or do I have to find the multiplicative identity? I was thinking about both cases and...

If we plot velocity in ms-1 over time in seconds, the gradient of the curve is acceleration or ms-2. If we plot time squared i.e. s x s over distance in metres, what are the units of the gradient? :redface:

If F is a field obtain all the units in F[x]?

I'm having great difficulties with CGS-units. In an experiment involving NMR I have to calculate the proton-proton distance in CaSO4.2H2O. I have done the measurements and they are, I think, pretty good however I have some problems with the calculations because of the units. The formula I...

I know I am not a moron but this C++ is killing me, I have to write a program using functions to convert temp between c, f, k I am hung up // Mod4project2tempconvert.cpp : Defines the entry point for the console application. #include <iostream> using namespace std; double ftemp (double...

Hi, We know that the SI unit for mass is the kg, and that for force is the Newton, where 1 N = 1 Kg x the acceleration due to gravity. On the other hand, the English unit for mass is the slug, and that for force is the pound, and again we have a similar relationship based on Newton's...

i think magnetic susceptibility xm=M/H is contant and independent of the units we are working with. in different refferences, they sometimes quote mks or cgs units which gives different value of Xm. It confuses me. Is Xm units dependent? for example Xm for oxygen is about 10^-4 in cgs...

I have a quesion regarding a quantum physics assignemnt, I wonder what units I should use when calculating the transmission coefficient of a quantum barrier problem. I have got the following expression: T = \frac{4(E+V_0)}{(2E+V_0)cos^2a\sqrt{\frac{2m}{\hbar^2}(E-V_0)} +...

I need to work out to dimensions that are derived from their fundamental units... I am having a small amount of trouble working out exactly how to do this... eg: Force Pressure Energy (using W.D.= force x distance) Thankyou for your time.

I know that Planck Time is the amount of time it takes light to cross Planck Length, but how did they figure out Planck Length? What are all the Planck units, how large are they, and how were they figured out?

can you imagine a system of base units* in which time was not included? *the system of base units is the following: quantity----------------------------name-----------symbol time--------------------------------second----------s length------------------------------meter------------m...

I realize these may be easy to some of you, but I'm have a few issues. For the first one: Two type of "barrel" units were in use in the 1920s in the United States. The apple barrel had a legally set volume of 7056 cubic inches. The cranberry barrel, 5826 inches. If a merchant sells 50...

Hello, perhaps you could help with a problem. Suppose a pulsar rotates once every 1.400 806 448 872 75 + or - 5 ms, where the trailing + or - 5 indicates the uncertainty in the last decimal place (it does not mean + or - 5ms). a. How many times does the pulsar rotate in 30.0 days? I...

Can someone help me with representing some quantities without units. I found that in atomic physics atomic units usually aren't used. For example Energy is E=\frac{-1}{n^2} Period of classical electron orbital i given by T=2 \pi n^3 Here n is Principial quantum number. How are derived these...

how is that homogenous with respect to units? i can't get it!

I would like to ask a question that I am having a hard time finding the answer to. This is my question: 1 volt per second equals 1 tesla per square meter equals 1000000000 nanotesla and yielding frequency of 42580000hz or 42.58mhz denotable through the proton precision frequency calculation...

Using cgs units, can I set c = h-bar =1 ? or should I change some other units to do that? Thanks

When finding the quantity of a radioactive substance remaining after a half life of time t, using the formula, T1/2=.693/lambda. do u have to convert the time to standard units, the second, if it is in mins, or yrs or days or months watever?

Hello all , I encouter a problem solving this one : We are given a conical pendulum with : V - tan. speed of particle m - mass of rotating particle g - gravity acceleration...

Hello. I am making a physics calculator, and I have to make a conversion Unit for the program. I need to know this (as an example) I need to convert Kilometers per hour to Meters per second. But no the usual way. I know that the conversion factor is 0.278 but I need to convert the...

What is with magnetic units used in published papers? You can only compare ~1% of the published results. Some of the units I've seen emu, emu/g, Arb, a few don't even give units. How do these papers make it through the review process?

i just need help with finding the units to a physics problem at the end. some examples... \sqrt{\frac{940N/m}{0.038kg}}*(0.25m) it comes out to 39m/s. i know that since it's velocity, it should always be m/s. but there are some question that i don't really know what the final units...

I am interested in a system of natural units that I see used more and more frequently in Quantum Gravity research papers so I like to try using them. the units are like conventional Planck except |8piG| = 1 I want to see if there is anything in the Cambridge Handbook of Physics Formulas...

Hi. Part of my homework was to work out what the SI base units of the gravitaional constant are. I'm crap at working out base units so could somebody help me out? Thanks If anyones wondering, G is 6.67 x 10ˉ¹¹ N m² kgˉ²

Let's say i have some function S(t) where t is in seconds and S(t) gives feet per second. As I take the derivatives of S to get the acceleration function, why is the feet unit squared? What's the best way to conceptualize what's going on?

Locus help please Just started this unit and don't have a clue as to what is happening. Here is the question Describe the locus points that are 3 units from line y = 2x – 3. Give the equation of the locus. Draw a diagram as well. Well I did a rough sketch of the line given and...

physics momentum problems Fred (mass 70.0kg) is running with the football at a speed of 4.70m/s when he is met head-on by Brutus (mass 130kg), who is moving at 8.10m/s. Brutus grabs Fred in a tight grip, and they fall to the ground. How far do they slide? Part A The coefficient of kinetic...

This is a quick graphing question. We have to graph Vout/Vin versus the log of frequency. Now the Vout/Vin would have no units but what about the log of frequency? Is it hertz or is it also unitless?

Starting fromthe equation \alpha=a/d with \alpha in radians and a and d in meters, show that the equation is also valid if \alpha is expressed in arcseconds, a is in AU and d is in parsecs. Would this be the proper way to show this? \alpha=a/d radians=meters/meters 4.8481*10^{-6} radians...

codons aren't basic units of the genetic code right? my friend told me that it does but i remember in lecture that proff said it doesn't but maybe i misheard

Alright, let's be real here Electrons are ejected from a metal surface with speeds ranging up to 4.71×105 m/s when light with a wavelength of lambda = 628 nm is used. What is the work function (in eV) of the surface? Alright, money, using the formula: Max Kinetic energy = hf - Eo where...

Units -- Watts, meters & Kelvin I have an equation: L = \sigma T^{4} * 4 \pi R^{2} Which I fill with values and units L=5.67*10^{-8} * (5860K)^{4} * 4 \pi * (6.96*10^{8}m)^{2} and I get an answer: 4.07*10^{26} K^{4} m^{2} The correct answer is: 4.07*10^{26} watts I don't...

velocity = 0.5 m/s radius = 1 m \omega = \frac{v}{r} \omega = \frac{0.5 m/s}{1 m} the meters cancel and I'm left with \omega = 0.5 s But \omega is supposed to be expressed in radians/s How do I get those output units with the given input units?

How do I convert 2.07*10^-15 Wb in MKS units into SI units? James

I am currently taking a Unit Operations course. The book and the instructor both refer to a unit, g mol (gram mol). The book defines molarity as 1 (g mol)/Liter. I am familiar with molarity but always in the past it was defined as mol/Liter. I do not understand what this unit is...

Consider : E = \int P(\tau) d\tau = \int A\delta(\tau) d\tau E is in Joules and P(\tau) is in Watts, what are the units of A? What about \delta? I have a hunch, but need to have all doubts removed.

It can be useful to construct and try out alternative systems of units---mind-broadening and you can get a different perspective on physics. And in several specialties they do this anyway because it is almost a precondition to being able to think. Whether QFT or Gen Rel they all have their own...

In the Halliday-Resnick textbooks, there is only mention of strength of a magnetic field, which in SI units is the derived unit Tesla. However, on my TI-89 and on more modern sources on the internet (including a Fuji-film PDF!), there is mention of the unit of the Oersted for magnetic field...

I was reading about the Planck units, and they said that Planck came up with them before his quantum theory of blackbady radiation, and before the constant h had been discovered. They said it's unclear how he found these units. This seems pretty weird to me. How did he come up with these...

Hi all, Sometimes I come across the units of mg/Nm3 for gas concentrations. What I would like to ask is why we need to specify that we are talking about mg per Normal cubic meter? Why not just mg per cubic meter? Whatś that Normal for? Thanks in advance. Billy_w

Hello out there! I'm a new guy here, so don't pick on me too much...I cry easy :wink: I want to show that a set of units in a ring forms a group under multiplication. What steps would I take to show this? Things that my feable brain knows: 1) if a is a unit, it is invertible and...

What does (kg)(m/s^2) = what unit? also does 1 cm^3= 1 mL? i forgot all these units stuff its really bugging up my mind

Here's my problem: Measured data for pressure versus volume during the expansion of gases within the cylinder of an internal combustion engine are given in the table below. Data Point p (bar) V (cubic cm) 1 15...