Helium Definition and 389 Threads

Homework Statement A light baloon filled wiht helium and with a density of 0.180kg/m^3 is tied to a light string of length L= 3.00m. The string is tied to the ground, forming an "inverted" simple pendulum. The balloon is displaced slightly from it's equillibrium position, as shown in picture...

Homework Statement What's the polarizability of liquid helium given: density= 145kgm^-3 relative permittivity = X = 1.0566 Homework Equations alpha (polarizability) = (3(permittivity of free space))/N) / ((X-1)/(X+2))The Attempt at a Solution because N is molecules/volume...

Homework Statement When you sing, the vocal folds in your throat act as a resonating cavity (one open end, one closed end) which allows only certain frequencies. Suppose you try to sing a pure tone which is detected by a microphone and measured to have a frequency 500.0 Hz. This is the...

Homework Statement A light spring of constant k= 90.0N/m is attatched to a table vertically. A 2.00g balloon is filled with helium (d= 0.180kg/m^3) to a volume of 5.00m^3 and is then connected to the spring, causing the spring to stretch as shown. Determine the distance L when the balloon is...

Homework Statement An empty rubber balloon has a mass of .0120 kg. The balloon is filled with helium at a density of .181 kg/m^3. At this density the balloon is spherical with a radius of .500m. If the filled balloon is fastened to a vertical line, what is the tension in the line...

Homework Statement I have a balloon with helium in it, I need to know the acceleration that it rises. It would be great if you could tell me what I need if I am missing any. This is what I have, Density of liquid(air) = 1 g/l Density of Helium = .1786 l/g Volume of Balloon = 91 cubic...

This is my first post here so hello to anybody who reads this! I just finished calculus based physics II this semester and there are a few things I want to design and make for myself to help better my understanding of what I learned in physics. One is device I have seen that generates an...

Suppose the neutron decay time n was 89 sec. AND the difference in rest mass between neutron to proton, Qn, was 0.129 MeV. What would the maximum Helium fraction, Yp, be?

[SOLVED] Helium and Balloons/Pressure Homework Statement A tank having a volume of 0.100 m3 contains helium gas at 120 atm. How many balloons can the tank blow up if each filled balloon is a sphere 0.300 m in diameter at an absolute pressure of 1.35 atm? What i know: V(tank)=.1m^3...

From Classical Mechanics by Taylor: "The Compton generator is a beautiful demonstration of the Coriolis force due to the Earth's rotation,... A narrow glass tube in the shape of a torus or ring (radius R of the ring >> radius of the tube) is filled with water, plus some dust particles to let...

Homework Statement (a) How many atoms of helium gas fill a balloon of diameter 29.4 cm at 23.5°C and 1.00 atm? (b) What is the average kinetic energy of the helium atoms? (c) What is the root-mean-square speed of the helium atoms? Homework Equations P=2/3[N/V][1/2mv^2]...

Hi! I have a project where I am supposed to model the s-process in a star in its Helium shell burning region, and i shall do this for a variation of neutron exposure, where neutron exposure are defined as: \tau = N* \Delta t , t is time. N is number density of neutrons. So I in...

Homework Statement What is the RMS speed of Helium atoms when the temperature of the Helium gas is 247 K? (Possibly useful constants: the atomic mass of Helium is 4.00 AMU, the Atomic Mass Unit is: 1 AMU = 1.66×10-27 kg, Boltzmann's constant is: kB = 1.38×10-23 J/K.) What would be the RMS...

First, I want to understand something. Everything I look at suggests that the ionization energy of an atom or ion is suppose to be the energy needed to remove the 'outermost electron'- which I find troubling conceptually, since they also refer to this as the one with the highest energy. Wouldn't...

Will Helium diffusion through stainless steel at 250 Deg C and approx 700 psi Delta P present any practical problem?

:-p http://www.cbc.ca/consumer/story/2007/09/26/helium-shortage.html

Helium Balloon Question! Hey I have a buoyancy question here, anyone know how to solve it? A 15 gram rubber balloon is filled with 18 L of Helium (density 0.179kg/m^3) and tied with a string to a child's wrist. Find the tension in the cord. The answer is 0.050N but what is the solution? Im not...

In most high temperature gas cooled reactor concepts it seems like helium is the preferred gas. But what makes helium a better chooise than nitrogen? :confused: And when on the topic of gas cooled graphite moderated reactors, what guarantees that the graphite will never catch fire? Is there...

Homework Statement A 1.10 g balloon is filled with helium gas until it becomes a 20.0 cm-diameter sphere. What maximum mass can be tied to the balloon (with a massless string) without the balloon sinking to the floor? Density of Air: 1.28 kg/m^3 Density of Helium gas : 0.18 kg/m^3 Volume of a...

Homework Statement Quantum mechanics makes the electrons-in-the-nucleus theory untenable (for example on helium nucleus where before they know that a neutron exist, they thought that it was composed of four protons and 2 electrons). A confined electron is a standing wave, whose wavelength in...

I'm currently doing a coursework in A2 Physics, on Zero Point Energy, and Casimir effect, and why doesn't Helium freeze at atmospheric pressure within micro-degrees of absolute zero. I've researched and I found out that only ZPE can account for the source of energy that prevents helium from...

Homework Statement A helium balloon has volume V0 and temperature T0 at sea level where the pressure is P0 and the air density is \rho_0. The balloon is allowed to float up in the air to altitude y where the temperature is T. (a) Show that the volume occupied by the balloon is then V =...

Does a hydrogen baloon ascend faster than a helium baloon? Ignoring the weight of the baloon fabric, and ignoring friction, but not ignoring the mass of the air, would a hydrogen baloon ascend twice as fast? Would the same logic apply to lead and aluminium weights falling through water...

What is the excitation energy of the He atom? I imagine this is also the energy of the photon released by the electron as it deexcites from the p orbital to the s orbital. I guess this would be different to ionisation energy as that refers to taking the electron away completely from the atom...

Homework Statement A certain organ pipe, open at both ends, produces a fundamental frequency of 275 Hz in air. If the pipe is filled with helium at the same temperature, what fundamental frequency f will it produce? Take the molar mass of air to be 28.8 g/mol and the molar mass of helium to...

Hello, I've got this problem: The sun converts 1.91exp19 kg of Hydrogen to Helium per year, given that the sun started out with 75% Hydrogen by mass, computer how long the sun would shine if it converts all it's Hydrogen to Helium. I computed the total energy of the sun as 3.81exp41...

Hello, I'm having trouble with this question: mass of proton= (1.674*10^-27)kg mass of neutron= (1.675*10^-27)kg mass of 4He= (6.648*10^-27)kg How many Kg of Hydrogen does the sun convert into Helium per year? Now my main problem is that I don't have the rate of conversion. I know...

Homework Statement What is the ionization energy for He+ Z=2 Homework Equations E = -13.6 z^2 / n^2 The Attempt at a Solution I plugged 2 in for Z and 1 in for n, and got 54.4 eV. I checked many charts and it said the ionization energy for Helium was around 24.6 eV.

Homework Statement A balloon 20 m in diameter is filled with helium at a gauge pressure of 2.0 atm. A man is standing in a basket suspended from the bottom of the balloon. A restraining cable attached to the basket keeps the balloon from rising. The balloon (not including the gas it...

Consider a helium atom where both electrons are replaced by identical charged particles of spin-1. Ignoring the motion of the nucleus, the Hamiltonian is [see attachment 1] Construct an energy level diagram ( qualitatively ) for this "atom", when both particles are in the n=1 state, and...

Ideal Gas Law Problem :) Homework Statement A balloon is filled with helium at a pressure of 1.0 x 10^5 Pa. The balloon is at a temperature of 23°C and has a radius of 0.13 m. (a) How many helium atoms are contained in the balloon? (b) Suppose we increase the number of helium atoms in...

Homework Statement Why is helium balloon in accelerating car tilting forward? Homework Equations The example that I think that I understand - is simple pendulum in accelerating car - and everything there is clear - g(effective)=g-A (all of them are vectors). The Attempt at a Solution So...

A spherical helium balloon is 2.5 m in diameter and has a total mass of 6.7 kg. When released into the U. S. Standard Atmosphere, at what altitude will it settle? My first thought was that diagram has the weight of the balloon acting downward, buoyant force upwards. -weight + Fb = 0...

How is this microscope going to be way way better than the electron microscope? Does anyone know the significance of this piece of equipment? Website links would also be nice... thanks

Helium Balloon Question...Help! A 600 kg weather balloon is designed to lift a 4000 kg package. What volume should the balloon have after being inflated with helium at standard temperature and pressure in order that the total load can be lifted? density of helium .179 and air is 1.29. I have...

I've been working on problem 12-3 in Kittel and Kroemer's "Thermal Physics", and I'm not sure I fully understand what is going on here. As far as I can tell, the system being described is something like this: Gas leaves a compressor at (Tc, Pc) and enters a heat exchanger. The gas leaves...

Hi, I have a question in a past exam paper which I can't quite understand how to prove. It reads: Give an expression for the Hamiltonian of the Helium atom. Neglecting the interaction between the electrons, derive the state function for the Helium ground state in terms of hydrogen-like...

Consider the helium atom which consists of two electrons orbiting a nucleus made up of two protons and two neutrons. If both electrons are at a distance of r = 3.1 × 10-11 m away from the nucleus, as in figure, what is the potential energy (in eV) of the helium atom? Treat the nucleus as...

I am curious about the physics behind why helium is or is not a good gas to use purging other solutions. I am explicitly interested in its effects with NO.

We're asked to make a rough order of magnitude estimate of this splitting. I know that it is caused by the coulomb interaction between the electrons. Therefore I estimated the potential between them as being V = (e^2)/(4*Pi*epsilon*a) where a =a0/2 a0 is the bohr radius I've assumed that...

In Helium we find that each energy level specified by (n,l) splits into two sub levels, a singlet and a triplet (this triplet is supposed to be degenerate) I'm sure that this triplet does not turn out to be degenerate because of fine structure. But I'm not sure if the fine structure splitting...

Sorry I am poor at using English to describe things. I hope you will patiently read my questions and answer them. 1. I saw some helium balloons today. We all know that if you do not hold the helium balloons, they will rise up to the sky. But today I saw a bundle of helium balloons (their...

I have a question about helium : If it is the most inert substance, why isn't it used more than krypton or argon for high-temperature incandescent bulbs? I don't see neon in light bulbs too often either.

A sample of helium behaves as an ideal gas as energy is added by heat at constant pressure from 273 K to 383 K. If the gas does 23.0 J of work, what is the mass of helium present? I tried this and think u use m=Q/c*change in T, but not sure where to go from there

Hi. I have been trying to do this question for about an hour now... A 0.12 kg balloon is filled with helium (density-0.179). If the balloon is a sphere with a radius of 5.2m what is the maximum weight it can lift. I tried using the P=M/V then Fb=pgV...No luck...Help..

Liquid helium is stored at its boiling-point temperature of 4.2 K in a spherical container (r = 0.251 m). The container is a perfect blackbody radiator. The container is surrounded by a spherical shield whose temperature is 72.8 K. A vacuum exists in the space between the container and shield...

A tank of volume 0.413 m3 contains 2.79 mol of helium gas at 5C. Assume that the helium behaves like as an ideal gas. The universal gas constant is 8.31451 J/Kmol, and Boltzmann's constant is 1.38066 x10^-23 J/K. Find the total thermal energy of the system. Answer in units of J. Would...

q,1: the hero of a western movie listens for an oncoming train by putting his ear to the trck. why does this method give an early warning of the approach of a train? a: My thaught are that any object that vibrates causes sound waves (due to compression waves in air..which are sound waves). so...

It may seem like my question should be in another board on periodic tables but I need answers from here. I'm hoping for vigorous criticism on a couple of deliberately annoying questions; 1) Why do the inner shells have a specific electron capacity - and the outer ones all the same ? 2)...

What do you think is better? Lets start a debate!