Can anyone Identify this...thing?

This came as part of a physics lab.  Can anyone identify this thing and where I might purchase a duplicate should I need one? Description: It's approximately 1 1/4 inches long and has two holes running through the center. It's made out of rubber.

Posted by Spaceman Spiff 8 years ago

Adding I'bles to the Physics Group

Plasmana and I have been going through the Instructables archives and adding appropriate I'bles to the Physics Group. If you have or find ones you think are appropriately, please help us out.

Posted by kelseymh 9 years ago

Physics, the good, the bad, and the ugly ?

I have been going through a site that has a lot of good things in it, but I am unable to confirm all of it. Has anyone ever read through this   Science/Physics miconceptions  site? 

Posted by Goodhart 7 years ago

Physics concepts flash animations

I stumbled on this site with all kinds of cool physics animations a few minutes ago. It has all sorts of animations illustrating physics concepts, from wave behavior to vectors to fluid mechanics to magnetism. It looks pretty cool. Some of the animations are more like just articles, and some are true animations. Requires flash to run.

Posted by Lithium Rain 9 years ago

Physics question has me stumped

A large crate sits on a pickup truck which has coefficients of friction mu(s) =0.6 and mu(k) =0.4 . My question is how do I calculate the impact velocity if the truck accelerates (-8.0 m/s^2) and the crate slides forward 1.5 m to impact the back of the truck? Can anyone please walk me through this problem whenever you get the chance? Thank you. 

Posted by GThreep 3 years ago


Seen on Imgur, A marriage proposal between two physicists.....

Posted by steveastrouk 5 years ago

A proposed projects for physics...

Hello there techies, the project USB charger was proposed by me to our professor in physics II. unfortunately he didn't accept such project HOWEVER he was happy. He just said that our project is not yet satisfying. He wants us to do a power inverter. We will buy a 2 6-volts battery and series it and it will output a 200+volts with a 30watts and then we will insert any charger such as a nokia cell phone charger and then voila, it should be charging. Do you think it is possible to do? And another project I proposed is that we will make a REAL TIME CLOCK using a 7 segment. I already had a schematic from youtube. and it uses a decade counter ICs but unfortunately I think such ICs are not available in our country, can you help us sir? T____T 

Posted by glennvontot 8 years ago

What a lot of science in a thin layer of gas.....

Spotted this fascinating article about "how the sky works"

Posted by steveastrouk 6 years ago

What say ye, Resident Physicist?

In which I ask Kelseymh his assessment of the experiment which they think may have detected neutrinos travelling faster than light. (Holy run-on sentence, Batman.) (Yes, I should have checked his orangeboard first...I'm a bad stalker. :P )

Posted by Lithium Rain 7 years ago

My Blender physics simulations!

Just for fun, I created a few physics simulations in blender, All of them of a building getting knocked down with various objects(meteor, plane, car, spheres). Here it is Here is my first one, It is older And included is a screenshot of the second simulation! :D Tell me what you think :) Thanks ~ReCreate

Posted by ReCreate 8 years ago

Phun -- "Coolest science toy ever?"

Phun - the 2D physics sandbox, has been called the "Coolest science toy ever" by the folks at Bad Science.Phun is a neat little physics simulation environment with gravity rules, etc., and a very simple real-time interface. Try it!The free download is here.

Posted by gmoon 10 years ago

Jargon ... it's not just for breakfast anymore

Here's the title and abstract of a preprint that was posted to arXiv yesterday. I have no certain idea of what it all mean, and I'm a practicing physicist! I just find the ratio of unintelligible jargon to English really amusing.Monopole and Topological Electron Dynamics in Adiabatic Spintronic and Graphene SystemsAuthors: S. G. Tan, M. B. A. Jalil, Takashi FujitaComments: 21 pagesSubjects: Quantum Physics (quant-ph)A unified theoretical treatment is presented to describe the physics of electron dynamics in semiconductor and graphene systems. Electron spin fast alignment with the Zeeman magnetic field (physical or effective) is treated as a form of adiabatic spin evolution which necessarily generates a monopole in magnetic space. One could transform this monopole into the physical and intuitive topological magnetic fields in the useful momentum (K) or real spaces (R). The physics of electron dynamics related to spin Hall, torque, oscillations and other technologically useful spinor effects can be inferred from the topological magnetic fields in spintronic, graphene and other SU(2) systems.

Posted by kelseymh 9 years ago

Racing Game Physics

I've been designing a physics engine for a racing game for a long time now (months? years?) and I think that I've finally got almost everything figured out. The one thing that I don't know about is traction. So far my best guess for a formula is T = X + (Y * S)Where T is the stabilizing force on the car, S is the amount of slippage, and X and Y are two of the car's stats (probably measured in G's). This formula would be applied to each tire separately to account for the suspension.NOTE: The thing that might not be obvious here is that the car doesn't slip at all as long as X isn't exceeded.What do you think of this?

Posted by yourcat 9 years ago

OE-Cake = Awesome

Hey you should check this out. h Here are a few videos for OE cake

Posted by dombeef 10 years ago

What the BLEEP do we know?

How many have viewed the movie or read any of the books enititled: What the BLEEP Do We Know? [ What the BLEEP link]I just viewed the shorter version of "Down the Rabbit Hole", and would like to have some opinion on whether it is worth my while to veiw the extended (6 DVD) version of it?

Posted by Goodhart 10 years ago

3D Domino Physics Simulation!

Just for fun, I made this little video. And these What do you think?Anyways, I made that using a Physics simulation DLL for Gamemaker.Rendered and everything on my Computer, I got Framerates a bit lower than 1(what do you expect with over 1000 Dominoes?), But the recorded video output is much faster than that.Enjoy!

Posted by ReCreate 9 years ago

See What's Really Happening in Physics --

If you are curious about what "real physicists" do, or what the current "hot topics" in research are, take a scan through the "recent postings" at the Physics Preprint Archive. Started for the High Energy Physics community in 1991 at Los Alamos National Lab under the name, and with a purely e-mail interface(!), arXiv moved to Cornell Univerisity with its creator in 2001.The archive includes preprints from all areas of physics research, not just HEP, as well as computer science, mathematics, and quantitative biology. "Preprints" are a way for the research community to get their results out for everyone to read, during the often lengthy period (months, sometimes!) between submission to a journal and actual publication. In many fields, it has been traditional for decades that printed copies of "preprints" were mailed out, sometimes in regular batches, between major University departments. That mechanism has been superseded almost exclusively by the arXiv database.Besides these traditional pre-publication journal articles, the archive also often includes conference proceedings, and submission of much older published papers of general interest to the community. There's also (usually in the general "physics" category) a scattering of crackpot nontraditional science papers.

Posted by kelseymh 9 years ago

School Project: Gravity Car Design

Hey there guys... In my physics class we have a project in which we have to make a gravity-powered vehicle that will carry a given load along a track. The vehicle can only be powered by gravity (weights) and cannot use any other energy source such as elastics, springs, explosives, etc. I have started to make a K'nex vehicle but it is not very sturdy. The following is a picture of the rules and specifications. Much help is appreciated. ThanksFullsize Images: Front PageBack Page

Posted by RaDiKaL 10 years ago

A strange new beast in the particle bestiary?

  Interesting article from the BBC website :- A particle accelerator in the US has shown compelling hints of a never-before-seen particle, researchers say.  The find must be more fully confirmed, but researchers at the Tevatron are racing to work through existing data.  If proved, it will be a completely new, unanticipated particle; researchers say it cannot be the much sought-after Higgs boson.  It could also signal a new fundamental force of nature, and the most radical change in physics for decades. The full article is HERE.

Posted by AndyGadget 7 years ago

Camera Stabilizer (Physics related)

I had an idea for a camera stabilizer a while ago which involves some basic rules of physics. I've done some thinking on it and I can't seem to figure out if it would really work or not. It involves two principles: 1.) Torque (t=f*d) 2.) Inertia (p=m*v) ---- The idea is to combine a gimbal design found on camera "gliders" like these: -Commercial product: -Homemade design: ...with some sort of see-saw to counter the effects of up-and-down motion.  Ignoring the fact that this might be somewhat hard to hold such a thing, I just want to know if this would work. ---- Any balanced see-saw will have an equal amount of torque on either side of the pivot point. Therefore, a balanced see-saw will work with 500g hung 10cm from either side of the pivot point, OR 750g 5cm from one side and 250g 15cm from the other side (750*5=3750; 250*15=3750).  With this concept, I thought of designing this part of the stabilizer like a small camera jib ( That is, the camera on one end with a counterweight on the other. The pivot point would have a handle or some kind of vehicle mount on it.  The stabilization occurs (or so I'm thinking) because of inertia. Inertia=mass*velocity. So, when the pivot point (the handle) moves up or down, one of the sides of the see saw should move up faster than the other. The side that moves up slower (the longer side of the see saw, I'm thinking) should have the camera mounted to it.  ---- Is there a flaw somewhere in my thinking? THE QUESTION: Would both sides of an uneven length, balanced see-saw move up at the same time when the pivot point is moved up or down? I'm not really sure and I'd like to hear your input. 

Posted by John Smith 6 years ago

water in 2 tanks

Hi, I have coffee machine with small water tank. i want to put large water tank next to it so i would not need to refill it every time. my problem is that the water tank in the machine is not sealed, so if i put more water with a hose from bigger tank it will spill out.. How can i create bigger water tank next to it so the smaller tank will refill automatically? Thanks, 

Posted by gabik 6 years ago

Multistage coilgun need help

I need help.  I was able to make a single stage coilgun, Now I have a few questions regarding extra phases. The coilgun i have has four 300+ Volt capacitors with capacity of 470 uf.  1)How do i activate them? Would it be possible to use a sensor switch like this? ( If not, what would you recomend? 2)Would it be possible to make it so that after projectile passes a secondary phase, the phase starts to recharge automaticaly?  Please help, and thank you!

Posted by mondeluz 3 years ago

Build your own demo of a particle accelerator!

This was originally posted by an I'bles user in the "Feedback" forum. I've suggested he repost his questions under Science, and hope to answer them there. In the mean time, this video from the March 2008 issue of Symmetry Magazine (a joint SLAC/Fermilab publication) is really cute. The original article's video includes a bunch of related items which are worth checking out themselves. The high voltage (at least 50kV, I think) DC supply needs to be pretty stable -- you can't just throw a rectifier bridge onto a wall cord, but other than that, the project would be extremely simple to build. I've sent Dr. Johnson an e-mail to see if I can get more detailed specs. Update 4 Jan 2009: Todd Johnson and I have exchanged a couple of e-mails about this project (d**n, I love the collegiality of the scientific world!). For the DC power supply, he used a potted module (i.e., an enclosed unit with no accessible or dangerous components) designed for use in a negative ion generator (like the "Ionic Breeze"). He bought the unit surpus from . The bowl you see in the video was custom made from acrylic. I thought something like a Pyrex mixing bowl would work, but the "corner" where the flat base joins the spherical body introduces a barrier to the ball doing what it should do. The coating on the ping-pong ball is something called "wire glue"], touted as a substitute for solder. For this project, he covered the conductive paint with some clear Krylon for protection. Dr. Johnson and I are discussing the possibility of collaborating on an Instructable for this project. As a result of the video publicity, he's already gotten some inquiries on how to build it, so this would be an appropriate venue. He has a substantial amount of performance data and physics background on the device, which we will include in the ultimate publication.

Posted by kelseymh 9 years ago

Quantum physics

Wow I was looking for some info on quantum physics and stumbled on this *cough* nut job *cough* and check this out *cough*Scam! *cough*

Posted by iman 10 years ago

From FB: Interesting info on trip to CERN

 Physics Hello, I work at CERN Education and Outreach and thought to share with you a video documenting the experiences of an inspiring physics teachers and his students from a trip to CERN. Here's the full article and video: Thank you, Angelos Alexopoulos

Posted by Goodhart 5 years ago

Is anyone familiar with an Euler's Disk? (physics, conservation of energy and angular momentum demonstration).

At this one site I haunt now and then, looking for new science toys and things to hack, I came across this little item called a Euler's Disk.  I am assuming at this point, that there is quite a bit of specificity in the way this needs to be made so that it works, thus the $25 price tag. Anyone have any information (not contained in the ad) on this?   It'd be most appreciated.  

Posted by Goodhart 8 years ago

Can someone tell me what Physics (and probably Engineering )is?

I am about to start my last year at school (1 September), with made me think of what am I going to do in a year. Before, I was sure that I want to do Physics in university, but somehow I realised that (probably) REAL Physics should have little connection with what I enjoy. I love tinkering with stuff, reading books and learning things from them (I learned all the STR I know by myself), making something funny (Tesla coils, ellipse compasses... You know the sort), learning how it all works, understanding things by finding and solving problems (my current topic is wet hydrodynamics), thinking about paradoxes, and solving puzzles.  It all seems like a game I love to play alone and with my friends, and which we occasionally teach to some younger kids.  My friends, who have just finished undergraduate year 1 can't tell me anything constructive, so can someone tell me what science is? I know the topic is a bit daft, but it's quite important for me. I will certainly ask the same thing everywhere and not once, but still...

Posted by gruffalo child 7 years ago

Are you in Florida?

At the moment, this is an extremely idle thought, but are there any active Instructablers in Florida, or cool science/tech places to visit with a group of teens studying physics? (apart from Canaveral, of course).   I am in the "wouldn't it be cool if" stage of planning a school trip with a colleague - we want to go and take selfies with rocketeers, but we need more than that to justify the trip as educational.  Official venues are good, but it would be kind of cool to be able to take them off-piste. Please do not take this question as a guarantee that the trip will happen, or that we will have time to meet with everybody who answers.  

Posted by Kiteman 2 years ago

Physicist proves that teleportation of energy is possible

A physicist has demonstrated that teleportation of energy is possible, a discovery that has profound implications for the study of physics.  Feb 5, 2010 Here is the link:  Physicists teleport energy And in case that doesn't work:  And, a link provided by LEMONIE that goes straight to the actual paper on the subject:    Energy-Entanglement Relation for Quantum Energy Teleportation - Masahiro Hotta     I don't know why that last link it not clickable though....      

Posted by Goodhart 8 years ago

Seven Hovercraft!

Hmm, seven different (but similar) hovercraft projects have been posted with a very short time.I wonder if somebody is using the site to document their science projects and get them judged by a wider audience?Why on earth did I not think of that??

Posted by Kiteman 9 years ago

What does the universe look like?

I watch these magnificent programs about the universe, so wonderfully explained by Morgan Freeman.  I am puzzled with one question.  How can the science predict the size of our galaxy in somewhat vivid details?  So, here is my analogy.  With the space technology at hand, taking a picture of our own galaxy is the same as taking a picture of the Empire State building from one of its balconies.  Can someone please elaborate on this subject. Thank you.

Posted by kabira 5 years ago

Any ideas or advice for a Rube Goldberg Device?

I need to construct a "Rube Goldberg apparatus that must incorporate a minimum of 5 different types of the six simple machines, and only one energy input to start the apparatus. It must actually accomplish a task. " My creative abilities are to say the least lacking. Do you have any ideas as to what I can do? Any websites you think would help? The people here are the cleverest on the internet so just share a little bit with me Please :-). Thank you.

Posted by indiegoober 10 years ago

Anti Gravity

SCIENTISTS in Finland are about to reveal details of the world's first anti-gravity device. Measuring about 12in across, the device is said to reduce significantly the weight of anything suspended over it.The claim - which has been rigorously examined by scientists, and is due to appear in a physics journal next month - could spark a technological revolution. By combating gravity, the most ubiquitous force in the universe, everything from transport to power generation could be transformed.The Sunday Telegraph has learned that Nasa, the American space agency, is taking the claims seriously, and is funding research into how the anti-gravity effect could be turned into a means of flight.The researchers at the Tampere University of Technology in Finland, who discovered the effect, say it could form the heart of a new power source, in which it is used to drive fluids past electricity-generating turbines.Other uses seem limited only by the imagination:Lifts in buildings could be replaced by devices built into the ground. People wanting to go up would simply activate the anti-gravity device - making themselves weightless - and with a gentle push ascend to the floor they want.Space-travel would become routine, as all the expense and danger of rocket technology is geared towards combatting the Earth's gravitation pull.By using the devices to raise fluids against gravity, and then conventional gravity to pull them back to earth against electricity-generating turbines, the devices could also revolutionise power generation.According to Dr Eugene Podkletnov, who led the research, the discovery was accidental. It emerged during routine work on so-called "superconductivity", the ability of some materials to lose their electrical resistance at very low temperatures. The team was carrying out tests on a rapidly spinning disc of superconducting ceramic suspended in the magnetic field of three electric coils, all enclosed in a low-temperature vessel called a cryostat."One of my friends came in and he was smoking his pipe," Dr Podkletnov said. "He put some smoke over the cryostat and we saw that the smoke was going to the ceiling all the time. It was amazing - we couldn't explain it."Tests showed a small drop in the weight of objects placed over the device, as if it were shielding the object from the effects of gravity - an effect deemed impossible by most scientists."We thought it might be a mistake," Dr Podkletnov said, "but we have taken every precaution". Yet the bizarre effects persisted. The team found that even the air pressure vertically above the device dropped slightly, with the effect detectable directly above the device on every floor of the laboratory.In recent years, many so-called "anti-gravity" devices have been put forward by both amateur and professional scientists, and all have been scorned by the establishment. What makes this latest claim different is that it has survived intense scrutiny by sceptical, independent experts, and has been accepted for publication by the Journal of Physics-D: Applied Physics, published by Britain's Institute of Physics.Even so, most scientists will not feel comfortable with the idea of anti-gravity until other teams repeat the experiments. Some scientists suspect the anti-gravity effect is a long-sought side-effect of Einstein's general theory of relativity, by which spinning objects can distort gravity. Until now it was thought the effect would be far too small to measure in the laboratory.However, Dr Ning Li, a senior research scientist at the University of Alabama, said that the atoms inside superconductors may magnify the effect enormously. Her research is funded by Nasa's Marshall Space Flight Centre at Huntsville, Alabama, and Whitt Brantley, the chief of Advanced Concepts Office there, said: "We're taking a look at it, because if we don't, we'll never know."The Finnish team is already expanding its programme, to see if it can amplify the anti-gravity effect. In its latest experiments, the team has measured a two per cent drop in the weight of objects suspended over the device - and double that if one device is suspended over another. If the team can increase the effect substantially, the commercial implications are enormous. Okay. lets throw down our ideas and see if we can figure something out... or not

Posted by RelyNupon 10 years ago

If you're standing on the Moon holding a pen, and you let go

Thought this deserved some looking at:can you answer these questions right?13. If you are standing on the Moon, and holding a rock, and you let it go, it will:(a) float away(b) float where it is(c) move sideways(d) fall to the ground(e) none of the above25. When the Apollo astronauts wre on the Moon, they did not fall off because:(a) the Earth's gravity extends to the Moon(b) the Moon has gravity(c) they wore heavy boots(d) they had safety ropes(e) they had spiked shoes My prediction is that most of you will get the question right, as instructables is a scientific community.Check the link for details

Posted by flio191 9 years ago

Take a look at this! 2 parabolic troughs combined to make a point focus!

Http:// is from a Swedish mathematician.He bounces light from one trough to the other to produce the point of light. Even if it is not as efficient as a parabolic dish (2 reflections instead of 1) it must be easier!He is just curving sheet material. I have made parabolic dishes and it is really hard to be exact enough and it is really hard to get the reflective material to go onto the dish without crinkling. So under "real life" amateur conditions, his apparatus is likely to be as efficient as a home made parabolic dish!He has more info and he has pdf files to download too.Great Idea. Hope someone makes an instructable.Brian White

Posted by gaiatechnician 9 years ago

Ask a Scientist Special Event: Phat Tuesday Physics Circus

Come join ringmaster Zeke Kossover and his crew of sensational sideshow scientists as they (and YOU) perform dazzling demonstrations that illustrate physical principles! Watch, and listen, as sound shatters a wine glass! Ride a hovercraft! Turn on an electric pickle! Try to look at invisible glass! Witness the stopping of time! (Ok, not time exactly, but the hands of a watch.) Zeke and his crew will astound, amaze and explain, every step of the way. Can you think of a more appropriate way to celebrate Mardi Gras, than sledgehammering a bed of nails into the chest of a physics teacher from New Orleans? I sure can't!RINGMASTER: Zeke Kossover, physics teacher at Jewish Community High School of the Bay.THE CREW: Tucker Hiatt, physics teacher at The Branson School and director of Wonderfest; Leif Steinhour, Constructor, One Off Shoppe.WHEN: Tuesday, February 5th, 7:00 pm WHERE: Axis Cafe, 1201 8th Street (btw. 16th & Irwin) Ask a Scientist recommends that you come early to make sure that you get a good view.

Posted by noahw 10 years ago

Physics Competition Car Design

Hey Everybody, I'm new to the community here, and i am hoping that with so many great minds on this site, some great ideas will be generated. the deal is, for a competition, my school needs to build a small car, around 1foot by 1foot, and it is propelled by three average sized rubber bands, it need to travel three meters straight, make a 90 degree right turn on the spot and travel 2 meters to stop in a parking zone, it has to turn and do the whole course unaided, Any great ideas? Thanks for helping me out

Posted by techball 10 years ago

How do Tokamaks work?

Ive been reading into the nuclear physics behind devices like tokamaks which are promising candidates for a viable fusion reactor. The thing is, from everything I've seen and read it looks like the popular model for a tokamak is only the in between stage. Its like describing the forces on an airplane in flight but neglecting to explain how it takes off or lands. Can anybody tell me how they get those things fired up and cooled down? And I dont mean the ignition process or simply turning off the input power. I mean how to get the gas inside the darn thing to stay in the containment field until its been ionized? or is it ionized already? Anything at all would be much appreciated. =]

Posted by Capn howdy 9 years ago

Hoax? A task not only for high-schoolers...

       Well, exept for being quite a fun thing to watch, it also should work as a great Physics problem for someone like me (or a bit younger)-studying all sorts of Mechanics and Newton's Laws to work on... The task is to estimate the acceleration the motorcycle should have to do it, and whether it's significantly larger than the one stated in some technical data (there is the motorcycle model somewhere in the video's name).        If you have a go on it and are a) school-aged and b) not sure you are right, PM me. If you simply want to share your results and/or opinion, write here (but try not to put any solution-I mean formulas). In case the video doesn't work

Posted by gruffalo child 7 years ago

Instructables HQ physical adress?

What's the Instructables HQ physical address? Now that Google is offering directions by walking, I can find out how long it would take me to trek halfway across the country...

Posted by KentsOkay 10 years ago

Received request for my physical address to qualify to receive an animated holiday card. Is this Legit? Why know physical address for this? Anyone else get one of these notices?

I received a notice from with request that I identify my physical address to qualify to receive an automated greeting card...???  Is this legit? Why do they need to know my physical address? This really sounds odd to me.  Anyone else get one of these kinds of notices?  I really LOVE   Its awesome fun for those who like to do projects not just talk about them.

Posted by BudBump 6 years ago

Computer program learns physics

From Wired:"In just over a day, a powerful computer program accomplished a feat that took physicists centuries to complete: extrapolating the laws of motion from a pendulum's swings.Developed by Cornell researchers, the program deduced the natural laws without a shred of knowledge about physics or geometry. ...Condensing rules from raw data has long been considered the province of human intuition, not machine intelligence. It could foreshadow an age in which scientists and programs work as equals to decipher datasets too complex for human analysis."LinkThe software has a long way to come, but apparently it's showing a lot of promise.What do you guys think? If computers can do physics better than humans, does that make human physicists obsolete?

Posted by drinkmorecoffee 9 years ago

Musical Junk Physics Project

This project is not for me. It is for someone who inquired on Answers. Here was his original text:It's a project for physics, and it sounds impossible. I also have to play it in front of the class and have a written component with an explanation on what resonance is occurring. No electric instruments.Objectives:1. Construct a musical instrument out of junk and common materials such as plastic pipe, wood, glass, metal scrap, etc.2. Demonstrate and explain physics concepts inherent in your instrument.Rules: 1. The instrument must be able to play an octave in tune to receive a B grade.The A grade is reserved for truly amazing instruments in terms of thought and construction, so my challenge to you is to WOW me.2. The instrument must be able to play a song. Songs such as "Mary had a Little Lamb" or "Twinkle Twinkle Little Star" are not adequate since they do not include all the notes in an octave. 3. No Kazoos, Jew's Harps, Pop bottles filled with water, musical saws, washtub basses etc. When in doubt, ask.4. This is a high school level assignment, so I am expecting high school level (or above) projects at an appropriate level of difficulty. 5. Grading will be based on # of notes playedability to make your instrument resonateappropriate difficulty of the instrument constructionyour song of choice in an auditory presentation to the class and an explanation of the physics behind your instrumentcreativity of course.Stringed instruments must have more than one stringLet's help him out!!!

Posted by BeanGolem 9 years ago

Oodalump's guide to performance K'nex guns

I just think this needs to be brought up again and seen some more.  Lots of very useful information in here for both new and experienced knex gun builders.  And no this is not outdated, do not look at the post date.  That is irrelevant.   Here you go, read through all of it.  All of it. This guide helped me a lot, and should help everyone else as well.

Posted by TheRacker 5 years ago

Dry Compass Needle Making

Hello.  I've been working on a project that I foolishly thought would be fairly simple.  It's a decorative compass, kind of.  The body was simple enough to make, but now I'm stuck on the needle.  I had researched the making of a permanent magnet and thought  the process was definitely do-able, but found out that with such a small piece of metal it's actually very difficult.  Then I did a little more research into compasses and learned that dry compasses do not work the same as wet compasses, mine is a dry compass.                 My question to all of you physicists and engineers is:  is it possible for someone to make a dry compass needle at home and, if so, how?                  I realize I could find a cheapish compass and pirate the needle, and will if I have to, but what fun is that? 

Posted by Attmos 4 years ago

New kind of contest launching January 24th

Starting this week, we will be running a new kind of mini-contest similar to the wonderful Weekly Challenges being run by mikeasaurus, scoochmaroo, and randofo. These new contests won't be too far out of the ordinary, but they're different enough I felt compelled to provide a heads-up to you loyal readers. Allow me to answer your imagined questions. What are these new contests called? Academic Challenges. What's the difference between these and a Weekly Challenge? The main difference is, um, academic. Project submissions should be usable by a teacher. I will include a list of the relevant standards for the subject matter, so pick one and make a hands-on project for it. Not too hard. We just need the answers to be useful in the classroom.  You can also submit a Guide. As long as the projects within the guide are all related to the topic of the Academic Challenge, that is. Just make sure every project is clearly tied to the academic standards we're looking for. (That'll put the majority of the work on hunting for good projects and writing good intros. Perfect for contestants who are too busy to make, but not too busy to search.) How long do these last? Two weeks. Or more, if two weeks isn't enough time to get some awesome and useful projects. But the first one will be two weeks, and the term of the contest will be clearly indicated on the contest page. What's the point of an Academic Challenge? To help build projects that teachers can use in demos or for hands-on projects with their classes. Well, that's cool I guess. Now what? Get your apples out, because the first Academic Challenge will be about Newtonian physics. And it starts tomorrow. Don't have any ideas? Was your last experience with Newtons primarily fig-based? Get hunting now for cool projects that demonstrate Isaac's big ideas and make a GUIDE. (I really want some guides, guys. Make guides.)

Posted by wilgubeast 6 years ago

Physics Illustrator on NON-tablet PC

Well, I've recieved a private message from well over fifty people in the past 30 days requesting that I re-compile and distribute the Physics Illustrator, so I got off my lazy butt this morning and made it. links are updated and working.

Posted by bleachworthy 10 years ago

"Knex War?" (The Math Bit)

Hey guy! Sharir1701 here and I just want to start off by saying that I'm not back into Knex warfare, but I have something to show you. About a year and a half ago, I posted this forum topic. There I explained why, in my opinion, just adding more rubber bands to a gun will not actually produce an overall better gun (past a certain, low point). I'm not getting back into that discussion, but I simply wanted to share something regarding that. Don't ask me how or why (I don't know, myself), but a few days ago I suddenly remembered that old assumption I made. Being a perfectionist, I hate leaving things unfinished or unexplained (particularly math and physics related inquiries). Back when I posted that topic, I had little to no formal Physics knowledge, and the beginnings of an understanding in mathematics. Now, I have a much broader understanding, much more knowledge, and an ability to explain and evaluate what I once couldn't. Anyway, what I'm trying to say is, back then, I didn't have the tools to prove my claims. I firmly believed in them, but I couldn't confirm them. It's nothing complicated, but, like I said, just something I'd like to share. I also want to point out that, although I personally don't enjoy spending days upon days perfecting a little plastic mechanism for firing (mostly) non-aerodynamic plastic projectiles, anymore, there still is a warm spot in my heart for the craft I once loved. More to the point - this is a small article just showing something I did in a few minutes the other day, that helps me to better understand how a Knex gun works. I hope that in writing this, more people that are still building guns, will think about more accurately calculating certain things about their guns to help improve their performance and hopefully produce more efficient guns. The final note I have is that I'm about to show you equations, all of which can be plugged with real, measurable numbers, to calculate to a high degree of accuracy, the forces at play. This means you can actually calculate the most efficient layout for a gun, and also that in designing your next, you will be able to use these equations, and many others, to find optimal solutions to your problems. So, what's all this fuss about? Well, basically, I just proved with a few, painfully easy equations that my conjecture about the forces in a gun, working on the pin, is true. I'll just get to it: First, Hooke's Law states that the force necessary to change the length of a spring or a (tense) rubber band is F=K*dX, where F is the force, dX is the distance you want to change, and K is a constant number, that each rubber band (or spring) has. You can quite easily measure both of these. For rubber bands connected parallel to each other (assuming they are the same type of rubber band, which ever is your chosen standard), this equation becomes F=K*dX*N, where N is the number of rubber bands used. dX and K are both constant in the regards of the pull of a pin on a standard Knex pin gun. Therefor, the amount of force required to cock a pin (pull it back to it's full length) is linearly correlated to the number of bands you put on your gun. Next, if we examine Newton's equation of work and energy, W=dE=F*dX, where W is the work, dE is the change in energy in your system (input from an external force, i.e. your hand), F is the force applied along a length of movement, and dX is that length. Let us define the base position of the pin (not cocked, minimum tension on the rubber bands, fully in the barrel, etc.) as having 0 energy. This then means that the work applied to the pin by cocking it is equal to all the potential energy it has. From this, plugging in the force, we get Ep=K*(dX)^2*N. Let us assume a perfect world, where we neglect the effects of friction and air resistance, and assume all the momentum of the pin is transferred into the bullet as it fires (I will briefly mention in the end, why everything we're neglecting here just strengthens my claim in reality, but let's continue for now). After being released (in other words, shot), the maximum velocity the pin reaches right before the end of it's journey can be found using the equation for kinetic energy Ek=1/2*M*(Vmax)^2, using the fact that (again, neglecting energy wasted as heat due to friction) the energy is conserved, as no external force is working on the system, which then means that Ep,start=Ek,end => K*(dX)^2*N=1/2*M*(Vmax)^2 => Vmax = sqrt(2*K*(dX)^2/M) * sqrt(N). The first sqrt term in the final equation is all one big constant (again, K is the ratio associated with the rubber band, dX is the distance the pin travels, and M is the mass of the pin), meaning we can conclude that (C for constant) Vmax=C*sqrt(N). Finally, force applied by a moving, massive object can be calculated using Newton's second law, F=dP/dT (P is the pin's momentum, T is the time it takes for the pin to go from velocity Vmax to 0, transferring all it's energy into the gun and the bullet, but as I said, let us assume all of it goes into the bullet), or F=M*dV/dT (M, mass of the pin, dV is the difference in velocity, Vmax-0, which is simply Vmax. This is because P=M*V, which means dP=M*dV, ignoring relativity). So, F=M*C/dT*sqrt(N). The time varies slightly, but insignificantly, so let us assume it is a constant. So that's it. The force exerted by the pin on the bullet is some constant (calculatable, as mentioned and as shown), times the sqrt of N, the number of rubber bands on the gun. So there you go. Just a little something I did out of the blue the other day and thought I would share a proof of my conjecture from what feels like eons ago. I hope you enjoyed. Finally, I would like to tell you guys, perhaps as a little tease, since I'm not sure if I will ever upload it, but I have made 1 more gun after I stopped posting. I have already slightly teased about it in my user info. I guess I'll tell you guys what it is if I'm already posting something here again :) Possibly my most enjoyable, most well received, and quite innovative gun of all time? The REMPAR-2. I built the REMPAR-3 (I was also going to call it S5 when I thought about posting it). In a brief summary, it's a pump action, chambering (or bolt action as I and many others falsely used to call it), magazine fed rifle, that's only 5 layers thick all over, except one tiny area where it's 8 layers thick (1.5 extra on either side), as a reinforcement, not necessary if you use less rubber bands. Oh, actually, there's another small necessary area where it's 7 layers thick, but it's tiny and doesn't make the gun look bulky at all, and who cares. Plus, the one is around the pump, which looks quite natural, and the other is "disguised" as a detachable sight (not really detachable) that also looks fine. It also looked fairly good for a gun that I made, it used (if I remember correctly) a grand total of 0 broken pieces, which is a big accomplishment for me (the mag has some broken white rods, but fuck off), and it worked flawlessly, reaching ranges over 80ft and being able to go at 2-4 rounds per second, depending on your skill level with it. In other words, I could shoot 4rps; My girlfriend, with no experience or practice, could do 2rps, which says something about the gun's comfortability and ease of use in my opinion. It shot blue rods up to an accuracy of about 5x5cm (2x2in) over 30ft, which is amazing for a Knex gun, and it was truly super comfortable. It wasn't even long at all, which is saying a lot, looking at some other people's attempts at 5-wide pump actions (I may also be guilty of an attempt several years ago). Being quite short and only 5 wide, it is also quite light. I'm sorry, I just really liked this gun, I think it was truly my best creation ever (of course, the S3 is by far the most innovative gun I've made, but it's mostly a concept gun, not meant for real effectiveness). I may post it in the future, but I'll make no promises. I suppose I won't leave you guys completely hanging and take a picture of it. Oh yes, there's also a neat, fun little thing I did, originally because I saw no other option, but then I actually really loved it. I'm talking about the mag-lock. It locks automatically (there's a band on it, but it ripped a long time ago, so...) and the mag cannot fall out. Then you pull on it with your middle finger, similar to a trigger, and the mag just drops right out. Love it :)

Posted by Sharir1701 3 years ago

String Theory,..this is not detailed, but what do you think?

Here is a short video (not embeddable, sorry) on the Higgs-Boson and string theory by Dr. Michio Kaku.  Comments?

Posted by Goodhart 6 years ago

Survey on Physical Computing and Microcontroller

Dear user, I need YOUR help in order to get some insight into the substance of microcontrollers and physical computing. The basic question that needs to be answered is, what the problems are that occur in the process of physical prototyping, what the reasons for these problems are, and how these problems can be avoided. The results will be used in a bachelor thesis, that deals with this topic, trying to find out how easy - or difficult - it is to enter that particular field. I kindly ask you to follow the following link and to participate at this survey. Thank you very much in advance! Vletsou Ioanna LMU - University of Munich  

Posted by asking-student 7 years ago