Lead Definition and 282 Threads

Hello, I would like to start by saying I'm not sure if this is the right forum for this, I created an account here today after positing to a friend of mine a random thought I had. I was enjoying a video on YouTube about the Berenstain Bears theory, that claims a large amount of people who are...

I am try to build a radio and find i just can not use the lead less solder, I have a 60 watt iron and the solder takes ages to melt and i get a lot of splatter, Is my iron powerful enough? I used to be very good with the lead solder.

According to this author, http://www.math.uic.edu/undergraduate/mathclub/talks/Weeks_AMM2001.pdf, a locally Minkowski spacetime with a nontrivial global topology may have a preferred inertial frame, in the sense that hypersurfaces of constant time can only be defined using particular time...

Hi, I am a student in the Netherlands, and I'll be attending university next year. However, I am doing some form of research on Quantum Computing with another student for our so-called "profielwerkstuk" but my understanding of Quantum Physics and math is sometimes not at the level that is...

Hi there PF, Say I get into SULI at Argonne (a current researcher there wants me to be in their group next summer and says it'll be pretty likely I'll get in). The work I do will of course be important, but does the brand name mean anything (to grad schools, employers like Intel/IBM, etc)...

Homework Statement A soccer ball is kicked. If there is a 3 meter high fence, that is 6 meters away, compute the angle of the kick and the magnitude of the velocity of a ball. Homework Equations a_y=-g v_y=-gt+v_y_0 s_y=-(1/2)gt^2+v_y_0(t) v_x is constant: we neglect air resistance. 6=v_x_0t...

Homework Statement Lead has a mass of 11.35 g per cubic centimeter of volume, and the mass of one of its atoms is 3.439×10-25 kg. If the atoms are spherical and tightly packed, what is the volume of an individual atom? ( m3) Homework Equations conversions The Attempt at a Solution For this...

Wikipedia states that "Savant syndrome results from damage to the left anterior temporal lobe, an area of the brain key in processing sensory input, recognizing objects and forming visual memories.", but if the area of the brain which processes sensory input get damaged how does the syndrome...

I can find information everywhere about his postulates but not how he came up with them either than the hydrogen spectrum.

Homework Statement Two uniform lead spheres each have mass 5000kg and radius 47cm. They are released from rest with their centres 1m apart and move under their mutual gravitational attraction. Show that they will collide in less than 425s. Homework Equations By Gauss' Law, force on a sphere...

I was informed I might get a better response by posting to this forum, so sorry for the double post. Hello all, I am currently attending a service course for a PET/CT system for my employer. We have been covering the physics behind the function of detectors and my instructor said something...

I am studying the history of Quantum Mechanics and was reading about particle entanglement. What I would like to know is how did Einstein see that particle Entanglement meant that particles would be affected by spooky action at a distance. I guess that spooky action at a distance may also be...

Homework Statement Lead is compressed reversibly and with temperature kept constant at 300K, and from pressure of 1bar to 1000 bar. Assuming the change in volume is small, what is the change in entropy S? Use the Maxwell relation derived from Gibbs free energy function. V = ##10^{-3}m^3##...

Hi I one of my application i am using the lead screw arrangement to lift 200kg weight using handle I used trapezoidal thread and nut. Could anybody suggest the diameter required for lifting the weight of 200kg

Homework Statement A 3.20 g lead bullet at 28.0°C is fired at a speed of 210 m/s into a large block of ice at 0°C, in which it becomes embedded. What mass of ice melts (g)? Homework Equations I thought that the KE of the bullet would be transferred into heatThe Attempt at a Solution I used...

Homework Statement 1. The question EthyleneDiamineTetra-acetate(##EDTA^{4-}##) is used in chemical analysis as a complex-former. ##EDTA^{4-}## is also used to treat heavy metal poisoning, as it forms water soluble complexes with them which can then be easily removed by the body. The reaction...

1. Homework Statement A block of wood has a mass of 3.47 kg and a density of 628 kg/m3. It is to be loaded with lead (1.13 × 104 kg/m3) so that it will float in water with 0.848 of its volume submerged. What mass of lead is needed if the lead is attached to (a) the top of the wood and (b) the...

We understand that for the Universe to be flat, the critical mass of everything that has mass must total an omega of 1.0. At first, with our lack of knowledge regarding dark energy, we thought that the universe that we detected (ordinary matter and dark matter) did not even add up to a third of...

https://www.yahoo.com/health/lead-poisoning-other-parts-michigan-222900551.html First, I actually lived in Michigan for 3.5 years (in Ann Arbor, Jackson and Ypsilanti), so I wonder if I could have been affected! Secondly, does lead poisoning only affect children? No teens/YA to full adults...

Why can't I charge my supercapacitor with 1 wire? If the ions in the electrolyte make up the opposite electroldes, why won't it store charge when I charge it with 1 wire? It makes since for it to hold less charge but it's not charging at all. I'm using a grounded battery. 1 wire to my...

Homework Statement What is the effect on the phase and gain margins of a system when a Phase Lead Controller/Compensator is added? Homework Equations I have designed the phase lead controller for the system so if anyone wants to see it, please ask The Attempt at a Solution I know, that in...

Homework Statement I was just wondering what was the general effect on phase and gain margins when a phase lead compensator was is added to a system. Homework EquationsThe Attempt at a Solution

i'm currently enrolled in a degree in biomedicine, i want to know whether i can do a master in bio medical engineering , the employability of the field and what sort of content is there in such a degree ?

Hello, according to the lead acid battery standard equations The overall chemical reaction is: At the negative terminal the charge and discharge reactions are: At the positive terminal the charge and discharge reactions are: My Q? If we empty all liquid from old battery and add H2O...

I had a thought a while ago, but it was removed because I cited a youtube video of physicists talking rather than papers, so I'll have another go. My thought was that the universe could be cyclical and infinite even if heat death is the eventual end of the universe as we know it. During the...

Homework Statement The standard entropy of lead at 25C is S(298)=64.80 J/Kmol. The heat capacity of solid lead is Cp(s) = 22.13 + .01172T + 0.96x105T-2. The heat capacity of liquid lead is Cp(l) = 32.51 - 0.00301T Melting point is 327.4C Heat of fusion is 4770J/mol. Calculate the standard...

I have read several articles about this topic, on Wikipedia but for example also this article http://supernova.lbl.gov/PDFs/PhysicsTodayArticle.pdf and also several books that discuss the subject. In very brief my understanding is that: - 1. When observing type 1a supernovae (standard candle) at...

Homework Statement A lead nucleus contains 207 nucleons (82 protons and 125 neutrons) packed tightly against each other. A single nucleon (proton or neutron) has a radius of about 1 ✕ 10^−15 m. (a) Calculate the approximate radius of the lead nucleus. (b) Calculate the approximate radius of...

Homework Statement Prove that applying an infinitesimal rotation of angle k<<1 around the axis x1, then a boost of speed -k along the axis x2 then the inverses of these is equal to a single boost of speed k^2 along the axis x3 The Attempt at a Solution Putting this into mathematical terms I...

I don't know pretty much about worm holes. but I have this doubt. Where do worm holes lead us to if we get into one?Do they lead us to a new but different universe or into some other part of this universe?

Homework Statement Homework Equations PCM ∑pi=∑pf v2=u2+2asThe Attempt at a Solution First, using the PCM equation, I found the final velocity of the block, which is about 10.5 ms-1. Then by using the SUVAT formula, i would be able to find the distance moved by the block, but I don't have...

I almost "get" it, but not quite. Can someone help? Here is my current understanding. Say you solve the Kronig-Penny model. You find that you get bands of N closely spaced energy levels, with large gaps between them. Under normal conditions, electrons fill the band to some level (let's say we...

I have a lead screw drive. The stepper motor puts out 280 oz-in of torque. Its attached to a 1/2 inch dia., .200" pitch, 2 start lead screw. There is a plate that's attached to the screw that moves back and forth along the screw. How much force can that metal plate exert in a linear motion?

Finally, got my new copy of Jackson's Classical Electrodynamics 3rd Ed. Took almost 40 days to come in from Amazon...Classmate said his copy won't be in until December. Is this becoming a trend??

Dear PF Forum, I have a question in mind. But I'm not sure if this belong to SR forum, cosmology or classical physics. So I post it here. And perhaps as some of you might have known before or thought it over. It's about kinetic energy. Supposed this... A rocket, with a rest mass 1 ton. And the...

Does an exchange of two identifical particles (electrons) lead to a new microscopic state?

(sorry - not sure about the prefix) I have read that lead shielding is dangerous against high energy particle radiation because of the high atomic number in lead. The particles would have high chance of hitting the lead atomic nuclei and producing x-rays. I am fed up with moon landing...

Hi, Could someone please tell me at which point in learning maths do you begin to write and solve proofs? I have taken high school maths so far except for discrete math. If there is a list of different maths that lead up to proof writing, please let me know of them and in which order I...

I'm trying to design a lead compensator for a double integrator plant, which is plant = tf([1],[1 0 0]) I started with the angle condition. So, poles contribute (+) angle and zeros contribute (-) angle and that sums to 180 Desired pole location is 4.4 +- 4.4j So, 45 + 45 = 90 degrees comes...

Hi I have built a gear drive for robotic arm that uses a worm set (worm gear +worm) at stage one. Worm (wheel) is of bronze and worm gear is steel haing a lead angle of appx 8 deg. This set is further coupled to a spur gear set that further increases the torque such that the over all gear ratio...

I've read that the Tsar Bomb used a lead casing for the second and third stages of the bomb instead of a uranium casing. A uranium casing would have resulted in fast fusion but would have created too much fallout. Typical Hydrogen bombs use uranium casings. A uranium casing would have indeed...

V' changes over time. How can I determine the influence from parasitic capacitance (~50 pF) on V? R wire ~ 100 ohm. If I need to read data (V' can change rapidly) from this at 50hz, does it influence reading accuracy? How can I determine values from which I need to be careful when reading data...

I know that for products produced in the EU and United States, I needn't worry about lead on components. That being said, I many times purchase products from Chinese sellers due to the low bulk price. I recently read that an electrical engineer with the tendency to chew wires while stripping...

Homework Statement An alpha particle with kinetic energy 15.0MeVmakes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude L=p0b, where p0 is the magnitude...

Homework Statement When lead is melted at atmospheric pressure, the melting point is 600K, the density decreases from 1.101x104 to 1.065x104 kgm-3. The latent heat is 24.5 kJ kg-1 Estimate the melting point of lead at a pressure of 100 atm. Homework Equations I haven't been able to find any...

Hi all, I'm a physicist, and I'm now trying to understand and model a problem with a multishafted cord, being pulled from one side in order to transfer force. The cord has its own elastic properties (elongation, bending etc.), it goes through several pulleys with friction, and most likely its...

Is it possible to sufficiently ground yourself just by touching the negative lead of a wire coming from a power supply once?

What is supposed to be the lifetime of lead against alpha decay? Notable light isotopes that DO undergo alpha decay: Be-8 188 keV 7*10ˇ-16 s Sm-146 2529 keV 103*10ˇ6 y U-235 4679 keV 704*10ˇ6 y U-238 4270 keV 4,47*10ˇ9 y Th-232 4083 keV 14,06*10ˇ9 y Sm-147 2310 keV 106,1*10ˇ9 y Pt-190 3252 keV...

So in a cnc machine, the screw that drives the x,y,z axiis are called "lead screws". I am constructing a machine that displences fluid at percise volumes. It will be essencially a seringe with one way valves coming in and going out. To open the "check valve" it requires at least 1.5 psi. If I am...

How is Lead being used in a nuclear power plant, is it done by the fission process or fussion? No equations are needed as this is an introductionary question into the atomic structures. Are the stable atoms unable to undergo fission/fussion? Please explain to me, how do I know if fission...