Why are screw threads designed so that screws are fastened when you turn it clockwise?\n\nIs that in any way related to moments, and the right-hand rule in Engineering?
119128
The short answer is standardization.  Most threads are righthanded so that people will turn them the same way to tighten or loosen them.  Probably the original (handmade) threads were righthanded because the majority of people are righthanded and more closing force can be exereted to tighten or shut in the clockwise direction.\n\nLefthanded threads are used for specialized applications such as on B-B-Q propane tanks to avoid connection to wrong fittings.  Also wheels on the left side of cars at one time used lefthanded threads because the forces on a wheel hub would tend to tighten vs loosen loose lug nuts.\n\nStandardization permits productiuon of threads with a minimum of machines (little duplication for right and left threads) and nuts and bolts can be stocked almost exclusively as righthanded.\n\nThe threads are not righthanded because of the "righthand rule of engineering" but the rule would not work without the standard thread convention.
151194
Unfortunately, I don't really have much information on this subject.  However, a galvanized nail (Galvanized is a protective layer around the outside of the screw to prevent rusting, or basic contact with the 'elements.') probably is the reason that the experiment is failed.  When will they start producing specific projects for these kids!?  Geesh.
256737
The simple answer?  For ease of calculations.  When you load a pinned truss, the only forces which will exist are along the axis of the members.  When you load a welded truss, however, there will be some forces generated by the bending of the members.  This would make the amount of additional information and calculation almost prohibitively difficult for the average person.  In most situations, the answers you need for design and analysis are close enough to the "pinned" answers, so engineers do it that way.  Does this cause some error?  Sure, but engineering is just a way to apply modeling equations to the real world, and comes with some errors anyway.  That's (one of the reasons) why they design with safety margins and factors...
300858
Did you know, when a man is having a suit made, one of the questions the tailor will ask is, "do you dress right or left?"  What he's asking is which side the customer's goods hang on.  And depending on the answer, the tailor will cut the pants a little fuller on that side.  Most men today, myself included, dress to the left.  In fact, I can't even imagine dressing to the right, so deeply ingrained is the habit.\n\nI know this doesn't really address your question (which, to be honest, kind of left me at a loss for words), but I thought it was a fascinating bit of trivia, being that we're on the subject of testicles and all.
463513
In the opposite direction of the applied force or motion
215229
eccentric gear and pin
4760
Its like an hook where u still have to do the fixing......that is why the inverted hook.
184390
You may be referring to the Coriolis Effect, which governs the rotation of very large fluids (like weather systems on earth), due to differential forces caused by the rotation of the Earth.  In a relatively small object like a pipe (or yes, even a toilet) the direction of rotation is either random or determined by the geometry of the object.
408811
let us understand it in a simple way:\n   Suppose you have a magnet as shown below:\n                                [ N ]\n                                [ S ]\n\nBy cutting the magnet centrally, if you  mean cutting it vertically, then we would obtain the following configuration after cutting the magnet:\n                              [N] [N]\n                              [S] [S]\nThat is to say we have resulted in two magnets with polarities as shown above.Now as we all know that like polarities(N-N, S-S) repel and unlike polarities(N-S,S-N) attract, the result follows that the two magnet in above configuration repel each other while they attract when one of them is rotated by 180.\n[When one of the magnet is  rotated (say the second one) the following configuration results:\n                            [N] [S]\n                            [S] [N]\nand hence the result.]
171565
first you must know that where are you use this information ? \nif calculate of force per leg is very important , you must make a static model which is include all dimensions et. and you can calculate forces  with use most useful static rules. \nexample rules \ntotal moment = always zero (every point)  \ntotal forces any direction (x,y,z) = always zero \netc. \n\nif solution not important you can accept 25 N per leg
346358
Have people never seen a real helicopter close by.... of course the rotors appear to go backwards... It is an optical illusion but it is exactly the same as a spinning bike wheel. When it reaches a certain speed the eye See's a part of it slow down and then it appear to go slowly backwards...... until it's just a blur again....\n\nI will go look for what the term for this is called and will be back with an edit shortly ;o)\n\nOK Back. I found this....\nImagine a clock with just a minute hand. If we were to look at the clock every 59 minutes it will appear to have gone backwards by one minute each time and if we look every sixty minutes it will appear not to have moved at all! So to accurately observe the minute hand in motion we must look at the clock more frequently than every sixty minutes, in fact we must look at it every thirty minutes. This is known as Nyquist's theorem.\n\nGraham
459566
Clockwork rely on spring tension to operate.  But when winding them, a ratchet prevents the spring from uncoiling from one end, so that it will instead push against the escape mechanism, which will slowly use the spring tension to drive the inner gears.\n\nAs for a site, you got me there.  That does not mean there isn't one, I just don't know of any specific one. But you can look what Leonardo Da Vinci did, that would be a good start.
136815
Rotational mechanics is a huge field and this space wouldn't be enough to explain it. Neverthless you can see this site for the topics it contains: http://www.batesville.k12.in.us/physics/phynet/Mechanics/RotMechanics/Rotate_Mech_Intro.html\n\nIf you want to know a specific think about Rotational Mechanics then ask that. If you don't know anything about it, then I suggest you buy a book and read about it.
573918
symetric properety...\n\n\nok heres why.....\n\n(pretend the equal signs are parallel line segments)\n\n===========================\n\n\ndo you see how you can split them dont the middle, thats called the symetric property
126996
Because algebra skills are very lacking in most people. It's just to make sure that they know what the rearranged formula's look like. But you are right, those 2 laws are probably all you need to remember. P=IE is always true, but remember than Ohm's Law is only an approximation for materials that have a linear E vs R graph, such as metals at room temperature. Its not true for semiconductors and gas discharges.
249064
There is often a wide divergence between theory and application.  I remember one application where lengthy mechanical linkages and cables were used to transmit rudder position for a huge seagoing ship in the even that the steering gear room became flooded (and electronic indication was lost).  The system had too much lost motion to indicate rudder position even though it looked good in theory.  I suggested connecting a vertical rod to the rudders that pierced the overhead into the ("unflooded") compartment above which could be connected to a reliable electronic transmitter (similar to existing "flooded" transmitters) and that worked much better.  Even electronic control systems can exhibit unexpected hysteresis when built.
596677
Don't let your right side - right arm over power.  You will make deep divots if you do.  Use your left arm for power, or at least try to keep it balanced.