Classical Physics

Can you calculate the exit velocity of a 25kg ferrous slug from a linear electromagnetic accelerator of a length of about one thousand metres when applied in a vacuum when superconductive electromagnets are used? Bonus question: Can you calculate the level of energy required (joules or volts, your choice) Extra question: Can you calculate the cost of this product? we can assume that there is not coating or anything, just a bare kilometre long linear electromagnetic accelerator. include source if possible.

A small balloon with a stone, stably suspending in the water, gently push it down, then release, it will: A. suspend in the position where it is released; B. go up and suspend at the original height; C. sink to the bottom of the container; D. float to the surface of water. The right answer is __ . I think the correct answer is B, but the most Chinese people believe the answer is C. My reason is that the balloon will go back to the balanced point. I put the question on many forums in China, and I am not persuaded. This question is famous because it often appears in the important exams, for example, the BIG exam for university entrance. Unfortunately, an…

If one pumped music in the form of pressurised gas perturbations emitted from speaker-shaped outlets, at an astronaut floating in space in front of them, would he hear the music through his helmet?

So, I'm an electronics guy and this problem has me stumped. If there's a cylinder of gas at 150 Bar, and I have a regulator on that cylinder. I'm pumping gas from 150 Bar to Atmospheric Pressure. What pressure does the regulator need to be set at in order to get 15 Liters per minute as my flow rate? I'm not even sure exactly how to set up this problem. It's a bit embarrassing, but it got me on this forum. Thanks! PS: Also, just so we can add some extra calculus here: Assuming a single-stage regulator, at what rate would my flow rate drop off as gas is being released? I love a chance to use second derivatives. So, again assuming a single-stage regulator, af…

A series of articles published recently (1) (2) described an effective shielding against a magnetic field. This effect is obtained by associating two concentric shells, one made of a superconductor, the other made of a ferromagnetic material. The shielding makes it possible to mask a volume from an external magnetic field or to dissimulate a magnetic field from the external world. It can in particular move away a magnetic pole from its opposite and thus to simulate a magnetic monopole artificially. Perhaps this magnetic shielding would make it possible to create an electromagnetic sail that means a system of propulsion which would use the natural magnetic fields, in p…

A hydrogen atom, vibrates at a frequency common to all hydrogen atoms, how does one measure that? Do we even have tech available to measure such frequencies?

Hi guys, I was wondering if someone could give me some specifics on how Solar Sails work. I understand them, I was just wondering if there is anything I should note when explaining these things. Also, would it be possible to build this? I mean, not counting the response of the public if we were to start funding a giant mirror....

The atomic tables indicates that nearly all elements/isotopes have a magnetic moment. But can a standard magnetometer register this?? or only permanent or changing magnetism?

Hi guys, I was wondering how fast the end of a giant pole starting at the center of earth would be if it was "x" miles long. Now I decided to try ang get this pole to the speed of light. This is assuming earth spins once every 24 hours, and that this pole would be able to withstand the centrifugal force. So assuming that light travels at 670,616,629 mph. Which means the circumference of the circle that would be drawn by the end of this pole would have to be 16,094,799,096 miles around. Which means the length of the pole would have to be (2.56×10 to the power of 9) miles long starting at the center of the earth. And if it was this long, then the exact end of it would be tr…

I found this video on the internet where they took a car airbag and put it under a turkey. When he set off the airbag, it shot the turkey at such a velocity that it broke the table that it was sitting on. My question is, how much force was applied to the table? Just to fill in a variable, lets just say that the turkey was 15 pounds. Here is the video that shows him getting the airbag and setting it up and the aftermath.

The news about the bending of space and the time wrap is almost a new thing. i have some of the ideas and posts to publish. Can any one help me in suggesting ways to publish my unpolished ideas??? I'm a undergraduate student,

Hi all, So I am a newbie on these forums and I am just starting to read James Trefil's book "Reading The Mind of God" --- In search of the Principle of Universality. Anyone else reading this book and any interesting discussions / insights ? I love science, especially physics and am planning to apply to school to study physics and mathematics ... My dream is to get into research at a top tier research university and also emigrate to the United States, the most powerful country in the world and a beacon of scientific , democratic and enlightenment values and human rights. Cai Gengyang

If the outside of a record spins faster than the inside then why doesn't the music slow down as the stylus moves inside

Hey friends. I hope someone can help me here because I'm starting to feel like I may be going crazy, and I hope someone can set me straight. My question comes in two parts: 1. Why does gravity often seem to have contradictory effects at different scales? The Earth is spinning at an extremely fast speed, while also moving through space at an extremely fast speed. This force called Gravity keeps me adhered to the Earth's surface, so it must be quite strong. I can easily imagine how strong a force would have to be to keep a tiny object adhered to the surface of a basketball while it was both spinning and moving. So I can empirically deduce that the pull of gravity must be …

Long, Long ago, I brought my idea for reversing entropy to my college thermodynamics professor. He couldn't figure out why I was wrong but kind of politely ushered me out of his office after an hour. Well, over three decades later, I want to cross this off my list. Would a physicist kindly review my thoughts and tell me why I'm wrong? I would greatly appreciate it and thank you in advance. The link is - Link removed Sincerely, Rob J Butwell

I saw a collection of glass 'ornaments' in a window display that were on a heat lamp and using evaporation/condensation to push bubbles and liquid (i think an alcohol) around a closed system. I was wondering if this is a physics demo item that has a specific name? The ornaments looked to be blown glass with glass tubing all standing about 15cms tall. I'd be grateful if anyone knows the name or where I can purchase these from online? Thanks! Dawn

1. Imagine a big river with water flowing constant velocity , assume there is a whirlpool at center as shown in the figure. 2. Because of the magnus force the whirlpool should move towards left or right towards river bank depending on the spin, but it does't happens it just stays fine in its position....so why? 3. I belive that magnus force will exists in whirlpool only when the velocity of water changes (acceleration), not just velocity , since the whirlpool is itself a part of the water flow. 4. apply the same to faraday's law of electromagnetic induction as anology ( magnetic feild as river and charge as whirlpool ) , is this correct?

Can metamaterial be perfeclty transperant on both sides. When you see it from one and from the other ?

I post it as a basic from the basics, as I see it. This a representation of a point standing still: Of course "standing still" is something physically frame dependent, it means for an observator named A (Albert, Alfred, Antony, Anastasia, Anyone), no displacement: Alfred sits on his chair doing nothing. We can represent the situation like this (you must have noticed I like diagrams): Antony (or was that Andrea?) is standing still. Better say A observes himself standing still. But there is something wrong here. No displacement in space is only one side of the "standing still" phenomena. Time is elapsing, no matter Anastasia is moving or not. So we have to repr…

I have a question about the forces and aerodynamics at play during a paraglider's flight. As I understand it normally flight can be thought of simply in terms of Thrust, Lift, Gravity and Drag. Imagining a paraglider in flight above a ridge, with no forward movement, remaining at a constant location relative to a spot on the ground. How does thrust apply in this situation? Is thrust even present? and if not what balances the forces of drag? How do the stated forces balance with respect to my stated normal understanding of aerodynamics? Thanks.

How do they differ? They both seem to imply resistance to change in velocity; direction and/or speed.

Hi, I am confused about what happens dring the impulse moment in collision between to objects-if a man is standing and the car hits him,does this mean it is an inelastic collision? and a part of the car's kinetic energy is transferred to the man?what is the difference though, between an iron man falling towards a concrete ground? does that mean that his kinetic energy is conserved from with in? and what exactly does this mean? Thanks

Does anyone know what property of a liquid is directly proportional to the volatiliy? I suspect that the specific gravity does since higher the density -> higher sp. gravity -> lower volatility. Looking from at the molecules again to try to explain (chemistry realm!): Larger molecules -> higher attractive forces between the molcules (Van der Waal) -> higher density and higher sp. gravity >>>>>>>>>>>>>> The chemical is less volatile.

If I boil (separately) 2 equally sized and equal age eggs, for the same length of time, but the water of one boiling furiously, and the other boiling more slowly (ie both at 100°C), does the hardness of the resulting egg remain the same?

An artificially created mini black holes could be huge source of energy for entire humanity - Stephen Hawking claims. http://www.express.co.uk/news/science/640496/End-of-the-world-Stephen-Hawking-black-hole-could-destroy-us Why does he believe that creation of such black holes will consume smaller amount of energy than what they would be able to provide later?