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Rocket Man

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Everything posted by Rocket Man

  1. the car has an omni directional transmitter, aka, a lightbulb. the rocket sees the lightbulb, the rocket actively modifies it's course to break said lightbulb. you don't need any triangulation.
  2. i say probably because you can seal up the end of a hose pipe with silicone. and yes, if the pressure were 100bar, the behaviour would be quite different. the compressible fluid in the pipe will attempt to occupy 1/100th of it's initial volume. such an attempt action is likely to rip the pipe around the silicone whilst pretty well inverting the tube. air is heavy. 100x air is very heavy.
  3. if you can hold lots of carbon dioxide at a few thousand degrees celcius for a few days you can flake a tiny bit off the bottom of the container. having said that, you can see why it's hard to find and costs a lot. bizmuth works too, it's just way less cool. unless you chill it (superconducts in liquid nitrogen, not very well though). bizmuth can be levitated above a suitably strong magnetic field, those magnets from a hard drive might work but you'll need a tiny flake of the bizmuth. i think you can buy it as shot, get one pellet and hammer it flat.
  4. the silicone probably won't move under 3bar, but if they move, they'll move into the pipe unless the pipe itself deforms. considering the rigidity of aquarium tubing, the pipe won't get crushed. the silicone probably won't go anywhere either. supposing the pipe deforms to match outside pressure, the silicone won't go anywhere (zero net force).
  5. the eye works at a reasonably fixed refresh rate, around 16 frames per second (take it as shutter speed on a camera, we see motion blur too) as the fan starts up, the eye sees the fan blade go around and around. but when you get up to higher speeds, the motion blur starts to overlap in funky ways such that you see a generalised motion slow to a stop and start moving backward. the blades aren't clear but the eye filters down to an illusion of motion. you'll see this with pretty much any camera, however, depending on the shutter speed and delay between frames, the images can be quite clear.
  6. i've read about a solid state tesla coil, the guy who built it linked the driver circuit to an audio amp. the arc behaved like a rudimentary plasma tweeter.
  7. nichrome wire makes for a very nice tension sensor. i think aircraft use this sort of thing to detect dangerous flex in the wing. but essentially, it's up to the designer to account for damage detection.
  8. a dead short is a particularly effective current shunt. have you seen one of those magnetic ring levitators? it's a coil with an extended core, the ring sits just above the coil due to eddie currents. if you put a red hot ring over it, it doesn't get enough induced current to lift due to resistance, put a chilled ring on it, it can barely sit over the core. a fuse gets to red heat just before it blows and becomes very resistive without actually cutting the supply. if the short is disconnected in time(befrore the fuse melts), the fuse will cool down and conduct normally. i'll bet that if you put a fuse on burnout on a current plot, you'll see a substantial dip before it cuts off completely. though i doubt mooeypoo is going to hold her fuses at red heat with just a bunch of battery chargers.
  9. use copper tubing like for hot water plumbing as the frame work, if you can find one to fit over your finger, you can use a type of rivet as hinges and solder cable mounts to it. it's strong, simple to make and extremely rigid. you could also line the inside with a resistive foam of sorts to measure the pressure your finger exerts on the inside of the tube to electrically control the cylinders.
  10. i'd be surprised if any animal had bone softer than cardboard at any stage of develpoment. you can snap a mosquito's exoskeleton without th use of pressure, but that's not a cut, that's snapping under force. you can't cut any thing harder than paper with paper in just the same way as you can't fashion a tungsten carbide tip using mild steel
  11. you only need one cylinder for the last two joints on every finger since they're controlled by the same muscle. where the finger meets the hand, you'll need a fair amount of force. that makes, to my count, eleven cylinders. three for the thumb since each joint can articulate independantly and two for each finger. the cylinders are going to be large. you can't avoid that, my suggestion is put the cylinders around your arm and run cables down to your fingers. (then think about redundance) you also need to think about the controll mechanism and valving. (use pneumatic, it's smaller) a word of warning, if you help your muscles, you'll need to help your bones. a hydraulic system isn't a nice thing to have tear you fingers off individually. you'll need a frame to mount the cylinders on that can only go through the motion your hand can and can handle all the force the hydraulics can muster.
  12. the motor acts as the current shunt, while the fuse become resistive at high temperatures
  13. that's going to depend on the speed of sound through the egg and holding meduim. if there's any big discrepancy, the egg's shell could get pulverised. however, the container can't create a high enough frequency of shock wave on impact to really matter to the egg (slow ramp up time due to the likelyhood of an uneven landing)
  14. speaking of bones, i'd like to pick one too. you can't cut bone with paper! the only reason a burr blade works is because the burrs are harder than the object getting cut. the only reason a hack saw works is because the teeth are harder than the object getting cut. any cutting tool you can find, i guarantee the blade is harder than the object getting cut. show me some experimental evidence that plastic coated cardboard, a very soft material can cut bone, a very hard material. cutting plaster board is different to bone and flesh. there's not much pressure you can apply to it before it starts crushing. if i had a sample, i would drive a card into it removing velocity from the equation to demonstrate that card is infact harder than plaster board. (and don't argue that plaster board is just brittle, "hardness" is measured by pressure)
  15. a brandy flame doesn't do much scorching. the thing that's important is the amount of heat the liquid soaks up as it evaporates. brandy evaporates fast enough to make a layer of cold alchohol vapour between the flame and the substance. the object soaked in brandy stays cold while the flame can boil water.
  16. ooh, i just rememered, vacuums etc have very high start up currents and fuses have minimum burnout times. as the fuse heats, the resistance increases reducing the overall power to the circuit. then motor manages to spin up to a low current level before the fuse actually blows. as the current in the circuit decreases agian, the fuse can cool reducing resistance restoring the power to the light. it's still a current shunt but it's sitting on the fuses burn limit. you can't sustain a current shunt if you have a fuse as spyman said so the only limit is where everything goes out. it will still work perfectly till then.
  17. read the first post, you can't use liquids. the ideal is a fluid that has the egg at neutral bouyancy with high viscousity. dense jelly for example. i did one of these, i used a butter container with cotton wool and air filled water bombs. it could probably handle 10m because of it's ridiculously low critical velocity. unfortunately, balloons are also out.
  18. if you have a disk or other cutting device, you can generally cut something softer than the disk material. paper cannot cut bone! i can see where this guy is coming from; since paper has a sort of grain, i'm thinking that a spin applies a slicing action to the subject, reducing the workload on a single portion of the card while also utilising the abrasive properties of cardboard. (paper cut) an impact with the edge of a card basically dents it and flattens the edge increasing surface area and reducing working pressure. the only problem with this theory is that mythbusters maximised both spin and velocity. if you check any high speed of a flying card, only one edge impacts. multiple impacts will move the card out of the existing slot making the first and most effective utterly useless. it's not about friction, or energy. it's about pressure and momentum. a diamond bur blade can cut bone and rock but is absolutely incapable of cutting skin and flesh. on hard objects, only a few diamonds touch the compund at a time. they have a minimum working pressure. skin increases the working area requiring far more pressure to do the cutting. it's the same for a card. if you take the edge of a playing card under a microscope you'll find it looks similar to a bur blade. efficient at cutting hard objects and poor at cutting elastic ones. the momentum serves only to apply greater forces for more time.
  19. well i don't know where you'd get someone certifiably insane enough to actually go on such a mission, but i'm sure they could get suitable superfluous gadgets right here.
  20. the technical term for that would be a "current shunt" you put too much load on a circuit, there's not enough current to go around. normally the fuse goes out before the circuit dips appreciably, but as for your workplace, it might be a little different. a wall socket is one of the simplest items you might chance across. its three wires attached between three bigger wires and three holes in the wall. draw too much current out, there's not much power left for the rest of the equipment. a number of wall sockets in close proximity has the same problem. except that instead of looking like a power board, it looks like an unfeasable number of wall sockets. a wall socket can generally give 10A. but if the wider circuit has too much load, you have a bigger problem
  21. if it comes up as a thread, it will probably have quite a lot of merit for discussion... i myself enjoy picking existing products to bits both metaphorically and literally. there's a number of products that could do with a complete overhaul and that often involves a lot of entertaining discussion. there have been a number of threads like this that did quite well. (if someone took a development team to this site they'd make a fortune)
  22. i didn't notice. that's definately a plasmoid http://en.wikipedia.org/wiki/Plasmoid what i want to know is how much energy they burned off making it and what it consisted of. because that was REALLY congruent
  23. if you get close to zero distance, you start seeing the poles on the electrons appreciably separated, try to get closer, you start seeing the electrons as wave forms with no discernable position according to the uncertainty principle. there's not really any thing paradoxical in magnetism, if you start drawing up rules for the marcoscopic, you'll find breaches every where. start by saying "magnetisim is due to motion of charged particles" then study the causes of ferromagnetism, diamagnetism, and all sorts of other effects. you'll find that when the microscopic is correct, the macroscopic behaves itself. a magnetic feild is a feild. it doesn't have a fixed relationship with distance. it took a brilliant mathmatician to prove that spherical bodies can be simplified to a point like source of gravity and net static charge. taking those for granted is a big mistake in the realm of magnetism.
  24. i've found that this board is used most by people who want to build something or find how something works. there's not normally much motive behind a thread to improve something unless someone can get something out of it.
  25. an led isn't boolean. there's below minimum voltage, there's too dim to read in, there's nominal voltage, and there's making the thing catch fire. much like a normal light bulb. there's a few posts detailing what is considered cheating, electromagnetics and voltage regulating wizardry is called cheating, yes. i also think it was "mass" that counted not weight, in which case, hydrogen contributes by 2.016 grams per mol of gas. now a nuclear battery might win it. though i doubt you could raid enough smoke detectors to accumulate the alpha or beta emmisions and hence, the current required to operate an led. i have a system encased in a few grams of wax, which can run a 4v led off a single flat AAA battery but that doesn't count.
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