Dust Definition and 172 Threads

Note: this is one of the suggested practice problems for my second-year classical mechanics course. Homework Statement A spherical asteroid of mass m_{0} and radius R, initially moving at speed v_{0}, encounters a stationary cloud of dust. As the asteroid moves through the cloud, it collects...

Homework Statement A spherical asteroid of mass m0 and radius, R, initially moving at speed v0, encounters a stationary cloud of dust. As the asteroid moves through the cloud, it collects all the dust that it hits, and slows down as a result. Ignore the increase in radius of the asteroid...

I am sure to those of you who know GR this will be a simplistic question. I can only hope there will be a simplistic and definitive answer :-) Assume a dust cloud of radius=5 and a mass =mc ANother equivalent mass of condenced matter md=mc with a radius=1 What would be the...

Entropy and Dust! I don't know if this goes here or in the Chemestry forum, I Want to Know Why a Closed House gets Filled with Dust...i have an Apartment in another state for vacation, we had´nt been there since 3 month ago...this past weekend we went and the Apartament which we left completely...

Hello! Right now I am trying to figure out how much of an affect dust has on the power production of some solar cells that I have. I was just searching for a possible material to use for dust testing. Anyone have any bright ideas?

Ok, I've looked a bit into your Posts. The problem is, I suck at math (i.e. differential geometry). So please tell me if I got the basics right (your post #6): The Minkowski basis vetors are \partial_t,\partial_r,\partial_\theta,\partial_\phi, with length 1,1,r,r \, \sin(\theta)...

Is a dust nucleus, dust attached to air? If water vapor molecules, attach themselves to dust nucleus in building visible [to the eye] snowflake, I'm supposing flake takes on shape of the dust. Does this mean "air" is shaped too? Don't laugh; I'm most confused!

The simplest frame Ansatz consistent with Hubble's discovery is: \begin{array}{rcl} \vec{e}_1 & = & \partial_t - f \, \left( x \, \partial_x + y \, \partial_y + z \, \partial_z \right) \\ \vec{e}_2 & = & \partial_x \\ \vec{e}_3 & = & \partial_y \\ \vec{e}_4 & = & \partial_z \end{array}...

If you had an infinite universe filled with a static, homogeneous, electrically neutral dust, the same in all directions, so that there are no forces to consider other than gravity, what would happen? Would it remain in that static state? I have two ways of thinking about it that lead to...

Homework Statement A small piece of dust of mass m = 1.6 g travels horizontally through an electric air cleaner in which the electric field is 508 N/C. The electric force on the particle is equal to the weight of the particle. a)What is the charge on the dust particle? b)If this charge is...

Say we have dust filled universe. At some instant of time this universe has a mass density rho, and it evolves with time according to General Relativity. Is there a quantity in that universe that acts like tension? Can we associate something like tension in such a universe. Would its strength...

Tuning the mass density of a closed dust filled universe can give us a long lived closed universe? General Relativity can tell us how that mass density changes with time? Instead of dust let us have a real field defined at each point of spacetime. Let us assume the field is such that in...

Say our early Universe had a significant fraction of its mass in the form of a uniform dust of plank mass black holes, along with the visible matter of our present universe. How might you figure such a dust would evolve in our early universe to our present epoch? Would such a dust clump just...

Homework Statement A magnet produces a 0.40 T field between its poles, directed horizontally to the east. A dust particle with charge q = -8.0×10-18 C is moving vertically downwards with a speed of 0.30 cm/s in this field. Whilst it is in the magnetic field, the dust particle is also in an...

Might absence of dust on moon (such as for astronauts' experience) relate to importance of material sciences? That is, might surfaces interact electronically, seeking a more stable lowest energy configuration? Imaging it as if 2 grates rubbing together, seeking best fit? Air might then disrupt...

The links I pull up assume that the reader knows what null dust is. Which I don't. An explanation would be appreciated. The question came up when looking for an (equally absent) clear explanation of Vaidya spacetime. This, in turn, came up while looking at the article...

Homework Statement A spherical asteroid of mass m_0 is moving freely in interstellar space (no external forces) with velocity v_0 . It runs into a dust cloud whose uniform density is \rho_d Assume that every particle of dust that hits the asteroid sticks to it and that the asteroid remains...

I realize that this topic is more towards chemistry however i was wondering why grain dust particles are explosive. Is there any carbon atoms in the dust particles that fuel these explosions?

I woke up this morning and the light was freaky! Everything seemed orange. Outside, the sky is pale orange, like fog but the wrong color. Trees a few houses across are fading into the orange ... we've got a dust storm. I live in Newcastle, a bit north of Sydney. This storm came up last night...

Why does Saturn's dust form a flat ring and not a sphere around it?

Homework Statement A small piece of dust of mass m = 1.6 g travels horizontally through an electric air cleaner in which the electric field is 511 N/C. The electric force on the particle is equal to the weight of the particle. What is the charge on the dust particle? If this charge is...

Homework Statement A uniform, spherical planet of mass M and radius R moves SLOWLY with an essentially uniform speed v through a cloud of interstellar dust particles, whose density is ρ. The dust particles are attracted towards the planet, and some of them would eventually fall onto its...

Homework Statement Imagine a planetesimal sweeping up small particles from a dust cloud. Suppose the planetesimal, of mass M and radius R, is moving through the cloud at a velocity v. There are nd dust particles per m3, each of mass md (a) Derive an expression for the number of collisions per...

Howdie. This question started from what was to be a "simple" analysis of heating the air in a room. So much for simplicity when you start to question what exactly is heat and what is happening to atoms and molecules. SOOOO...the question I have (which will have bearing on my INITIAL quest)...

hi, i'm trying to find a way to attract small dust particles in a household environment to a surface. i have no physics and no engineering skills whatsoever so this is all new to me, but what i am wanting to do is have a surface with a constant charge, as perhaps this is the way to achieve this...

hi, i have some questions about static charges and to see if anyone is able to help me with an experiment. i am pretty naive about this stuff, so please excuse my ignorance if i ask you any silly questions in response to suggestions. i want to create some sort of charge on a surface (about...

is it also due to solar wind? if so why is it in a different direction than the gaz tail?

Hi, I am more familiar with the world of biology and chemistry, however I am trying to come up with a method to evenly distribute dust over a surface area which may require a bit of Physics help. I was wondering is there any way of say, positively charging an aluminium foil surface and...

As I understand it, the conclusion that our spatially flat universe is expanding at an accelerating rate is supported by observations of 'standard candles' (type S1a supernovae) which appear less bright than expected when their z exceeds about 0.3 --- . Robert Kirschner has discussed these...

http://www.cnn.com/2009/POLITICS/02/25/jindal.reaction/?iref=mpstoryview Is this the best the Republicans can offer? That was a train wreck last night. I think his sing-song condescending response was dreadful. Sara Palin has pretty much soiled herself after getting demolished in the General...

Fountain of Mysterious Space Dust Found http://news.yahoo.com/s/space/fountainofmysteriousspacedustfound Mystery of Red Space Glow Solved (06 April 2007) http://www.space.com/scienceastronomy/070406_red_rectangle.html Dying Star (HD 44179, "Red Rectangle") Sculpts Rungs of Gas and...

Homework Statement A star surrounded by a sphere of dust with a radius R. The star emits a short bright flash of light, it is absorbed and re-emitted by the dust. Someone much further away than R sees the light, first at a point on the shell and then in an expanding ring. A)Show that the...

calculate the rms (root-mean-square) speed v_rms of these particles, assuming them to be spheres of diameter 5 \; \mu {\rm m} and density 2 \; {\rm g}/{\rm cm}^3 = 2000 \; {\rm kg}/{\rm m^3}. The mass of such a dust particle is 1.31 \times 10^{-13} \; \rm kg. Express your answer in millimeters...

A diagram shows many very small dust particles suspended in the gas in a closed transparent glass. Question: Explain why dust particles stay suspended in the gas and do not fall to the bottom of the syringe. My answer: Dust particles are constantly being bombarded by free moving gas...

So this is a problem my friend was doing. I don't remember the specific values for the variables, but it should be ok. There is a speck of dust floating above an infinite plane. The speck of dust has a charge q1. The plane has a charge density of sigma= xC/m^2. What is the mass of the speck of...

More dust in the air presumably means that there are more nuclei on which water molecules can condense to form liquid water.Water vapour is a greenhouse gas so can the current trend in global warming be attributed to less dust in the air than usual resulting in more water vapour and higher...

What is ...Dust? I know this is quite ackward and may not be the right place to ask such a question but I am a bit curious to know something good about it: Earth is composed of soil; Soil is a mixture of elements and compounds; But we don't use the soil around us to extract those compounds...

Hey there Could anybody answer the following question on dust grains and depletion of Silicon and Carbon on dust: If D(Si)=-3, D(C)=-0.5, and the logarithmic cosmic abundances of Silicon and carbon relative to H as 12 are 7.5 and 8.5 respectively, what is the ratio of the number of atoms of...

I was wondering what is happening with Earth accumulating dust and other debris from outer space? This must change earth’s weight? What is the rate of this accumulation of weight? The same thing must be happening to the sun, surely in proportion to the gravity field of the sun, so probably all...

[SOLVED] Force on Particle in Dust Cloud The following problem is from Thorton & Marion's Classical Dynamics, Ch. 5 Problem 5-13 (p. 205 in the 5th edition of the text) Homework Statement A planet of density \rho_{1} (spherical core, radius R_{1}) with a thick spherical cloud of dust (density...

http://www.ciw.edu/news/dirty_space_and_supernovae

You have charged dust (pressure = 0, charge density/mass density = given constant). I suppose the total energy-momentum tensor of that system (including the rest energy and the EM field) cannot be expressed simply in terms of the arbitrary 4-velocity of the dust like for example the case of...

Any ideas on how to build a device that captures dust from the air? My room is full of it because I store all my clothes here, and I can't keep the window open for long as it's winter and it's really cold...

if space contains space dust, wouldn't the space dust be a medium for sound to travel?

Homework Statement An empty bucket (mass M, area A) is launched with velocity v0 from a space station into a cloud of dust (density ρ). As the bucket moves through the dust it will collect dust in it until the bucket comes to a stop. Solve the place of the bucket x=x(t). 2. The attempt at a...

In terms of physics, why is dust attracted to CD's after they are wiped with a dry cloth?

Homework Statement Suppose that the density of interstellar dust is uniform along the direction of the plane of the galaxy, but that its vertical density is given approximately by \rho = \rho \o exp - ( z / 0.15 )^2 where z is the distance from the plane of our galaxy in kpc. If the...

What a great forum. I'm prototyping a small hand-held 110V tool. I need to add an electrostatic discharge function to it. We have all seen the "Ionic filter" devices at Sharper Image, where the plates will charge and attract dust. This is the opposite functionality - I need to push dust...

Homework Statement Find the KE of a dust particle that weighs 1 micrograms traveling at a speed of 1 mm/s Homework Equations E = \frac{mv^2}{2} The Attempt at a Solution Would this question be applicable to the equation listed above? I thought it was only applicable to electrons...

http://www.physorg.com/news105869123.html