Classical Physics

That is a surprise, The momentum of an object traveling in a circle has angular momentum and that is conserved. I listened to a lecture on that the day before yesterday. If you work out its instantaneous momentum the same amount of momentum is present the next moment but at different direction, true, but that is allowed under angular momentum rules. We allow friction to be part of the centripetal force but that only appears if the object is pushed over another surface. So what is the push force that makes friction into a centripetal force?

They talk about a bullet getting extra velocity when fired along the direction of travel, and likewise slowed when fired to the rear. But what happens to a bullet fired from a gun either moving sideways or rotated (swung sideways) rapidly. I saw a YT where the Mythbusters proved a bullet does not curve in flight after being fired from a gun being swung around rapidly. I had a feeling if a gun is being swung at the same time as being fired, the gun momentarily stops, or slows at least, for there is no way to add the angular momentum to the bullet in the short time it is within the barrel. Any ideas?

We have had umpteen threads about forces and accelerations on rotating bodies, without result, so here is a question for those who think they know. Put a cup, half full of tea, on the outer edge of a motorised lazy susan and spin. What will happen to the surface of the tea in the cup. Will it rise up one side, if so up the inner (close to the centre) or the outer? What does this mean for the centrifugal v centripetal argument? I have tried to find a video of this experiment without success. I can only find videos showing the vortex created by spinning the cup about its own axis. So I woudl be grateful if anyone can offer one.

J -- -- -- --o | | | | | | o Attached on a 1 unit long and weightless cord are 2 identical balls w/ 1 unit mass. If it slides on hook J w/out friction.. the high ball can be pulled horizontally to distance (d) away from J so that when released it can hit the other ball. Can I assume that the low ball is at rest on time of collision?

I am reading a book that mentioned that in the early 1900's it was believed that an ether was thought necessary. After thinking about why they thought it was necessary, and the fact that no one can seem to find any. I wondered if the reason they couldn't find any was because they expected a medium or field of mass particles, so in essence they were looking for they were wrong clues. Action at a distance was thought to be improbable. Then I thought of all they needed was a medium, that space itself wasn't sufficient then what about time? What if they already had what they were looking for but couldn't see it because they were expecting more. So now the question. Is sp…

If there is a permanent magnet and an electromagnet 1 light year apart and separated by the vacuum of space, and say the electromagnet has been running for a number of years and it and the permanent magnet are attracted to one another, and then the electromagnet is turned off, will the permanent magnet "feel" this change in less than 1 year? Will the permanent magnet still remain attracted to the electromagnet for 1 year longer even though the electromagnet has been turned off?

Newton divided the spectrum into seven named colors: red, orange, yellow, green, blue, indigo, and violet, but I think it is not correct. I think light is only consist of three colors, red , green and blue and it is not consist of seven color or more. The reason is when light dispersed by prism, there are overlap by red, green and blue. If light only have one kind of color light, and it through a prism, the result should be below. If light is consist of two kind of color light. If light is consist of three kind of color light. We know that when three primary color combine, they can form other color. when red combine with green, it become yellow…

The magnetic field of the neutral zone - The emergence of electric current in the conducting loop, moving in a magnetic field of the neutral zone. In the center of the copper coil inserting a sharp iron core. Touching the tip of the core center of the neutral zone of the magnetic cubes bipolar magnet with axial magnetization and reciprocating motion without air gap parallel to the internal lines of force of the magnet, about 1/10 of the area of ​​the neutral zone - an electric current. (The physical picture of the current occurrence is not defined). When you zoom in and out of the neutral zone of the permanent magnet to the iron core copper coil - current appears n…

Could someone help me understand the Boltzmann factor?

Why do impurities lower the melting point of solids in molecular terms ? Can a solid be doped with a material which will reverse this process ?

Sorry Strange, I thought I made myself clearer, but I guess not. Things farther away actually weigh less because weight is a force due to gravity and changes with the inverse of the radius squared. In effect, the equatorial surface is feeling less gravitational force Mass does not change, and the two are not the same.

Do you think that can be taken to the limit with the whole Earth as a spread out circular sheet will the gravity always be stronger at the center?

I was watching this clip for the first time (Brian Cox visits the world's biggest vacuum chamber), https://www.youtube.com/watch?v=E43-CfukEgs. I was wondering what would happen if you go inside the chamber with a space suit and try to jump: would you jump higher because of less air resistance?

Are gels solids, liquids or semi-solids ? Please explain.

This is just a silly idea of mine, so dont get ahead of yourself. Lets say we have a pipe that's 1 km tall and its filled with distilled water, its standing up and it is made of a material that has the required compressive, tensile and shearing strengths for it not to collapse or break apart, also its in perfect equilibrum. Next, through a double door mechanism, we introduce an object that has lower density than distilled water so it floats, eventually getting up to the tip of the pipe. Then we let it fall through another 1 km pipe that has a dynamo every 5m, slowing down the object and transforming its kinetic energy into electricity until it hits the ground, the…

This post results from the problem posed in another thread: http://www.scienceforums.net/topic/88301-earth-what-is-the-real-age/page-6#entry861043 If two planets each 1/2 the mass of the Earth collide what is their terminal velocity? This would depend if one planet was falling toward the Sun so it could have a velocity over and above that caused by the mutual attraction. (So we will have to ignore this additional velocity in the meantime.) I saw one statement that said: https://books.google.co.nz/books?id=0iggAwAAQBAJ&pg=PA427&lpg=PA427&dq=potential+energy+planets+colliding&source=bl&ots=MQYOmb0bj2&sig=cLZQMP-V8pwzhPi220UakLldSVA&am…

We all know that water has maximum density at 4 degree C. What molecular property of water can explain this ?

Does an electron radiate while being accelerated by an electrostatic force or gravitational force? The posts here say it always radiates when accelerated. It has been demonstrated that electromagnetic force causes the electron to radiate. Is there an experiment that determines the result of electrostatic force? This item on the internet seems to contend that acceleration doesn’t always cause the electron to accelerate. Will the real answer please stand up? (You aren’t old enough to remember that show.) The physics Hypertxtbook 1998-2013 Glenn Elert X-rays are produced whenever fast moving elect…

I was reading about the fact that many of the planets so far discovered in the rocky planet category are know as super earths, some are estimated to have gravity 4X earths surface gravity or more. If we had been dealing with 4 g surface gravity how much harder would the apollo missions have been? Would it as been as straightforward as 4 X as big a rocket or is the difference more likely 8 X?

Hi, I just came about this video: https://www.youtube.com/watch?v=FsAA8yY0lP8 on BBC documentary. The Video shows A Trick: Using several Hammers, Rubber bands and Rulers a system is build, in which the sum of all torques is equal zero. The appearance of this system is awesome.

In a u shape tube of one inch diameter if we add some mercury(*) what will be the minimum height of water(: ) to increase the mercury level by 1 inch |:|...........| | |:|...........| | |:|...........| | |:|...........| | |:|...........| | |:|...........| | |:|...........| | \*\____ /*/ .\ ******* /

*Suggestions for Water Production for California.* California is still in the midst of a huge drought: Annie Sneed Science 03.23.15 7:00 am California’s About to Run Out of Water. We Have to Act Now. http://www.wired.com/2015/03/californias-run-water-act-now/ There appear to be however relatively simple methods of providing extra water. One is by deriving water from humidity in the air, the other by distilling the water from the ocean. Both would appear to have relatively low cost solutions. First the humidity solution. The amount of water in the form of water vapor is substantial, especially at high humidity. A key fact is air can store more water vapor at hig…

Ok this is driving me nuts... Metals are generally held together by metallic bonds where they all share a big cloud of electrons (I know this isn't totally accurate and of course there are exceptions but bear with me for the sake of argument)... I also know that metals (with the exception of certain amorphous solids like the SIM door tool for the iPhone 3gs) are organized in a specific pretty dense crystalline structure... My question is, since metallic bonds are pretty flexible with the whole electron cloud thing, what prevents two pieces of solid metal from becoming one at room temperature? I know surface morphology, oxidation layers and a bunch of stuff would prevent i…

If classical thermodynamics deals with macro states, why do we care how the heat transfer occurs? My understanding suggests that how the heat is transferred is irrelevant? All we care about are the final states of the systems after an equilibrium is reached? If we're not at equilibrium then we simply wait for equilibrium to occur. Why make the distinction?

If we take a gas thermometer and cool it to absolute zero, the pressure vanishes. What happens to volume? The way I see it, it can't be zero, however on a PV vs T graph, 0 x V = 0 so volume can be anything but at the end of the day the 0 pressure multiplies by volume and yields 0. So, here's where the algebra comes in that I'm getting confused over... Comparing two gas thermometers (one much larger than another) both initially at room temp... the first one is of a volume of 1m^3 and is argon and another one we have equaling to 5cm^3 and is helium. Then they are both cooled. At some point your pressure goes to zero, whatever that means because how do you even measu…