How can a spring generate constant speed of a wheel?
338513
"Constant speed" is an ideal and cannot be achieved perfectly.\n\nHowever, there are ways to achieve speed regulation in a spring driven system that are constant enough to be useful. The spring-driven clock is a good example. It is accurate enough to keep time for day-to-day purposes but is not perfect. As the mainspring unwinds the watch will slow down ever so slightly.\n\nI cannot think of any energy system that is used by man that does not have some scheme for regulating the power source by negative feedback. Can you?\n\nWK
648293
This is a magnetic flywheel.  The spinning magnets will induce a voltage across the coil of wire.  If you draw current from the wire, that current will induce a magnetic field which will exert a torque on the magnets, slowing them down.  The total electrical energy you can get out of the system will never exceed the initial kinetic energy of the rotating magnets.\n\nThe thing slowing down the magnets is not friction, it's an electromagnetic force, and even if you eliminate friction completely, the magnetic torque will spin down your magnets quite handily as soon as you start extracting energy from the system.
476332
A spring can be made of many different materials, it is usually of higher carbon steels heated and then quenched at a proper rate to give you the spring constant that you want.
575330
In brief.... friction.\n\nBasically, there is friction at the hub of the wheel which is acting as a force that slows down the wheel. In addition, there is also friction between the wheel and the air surrounding it (often called wind resistance). The two forces will eventually stop the wheel.
1009948
perpetual motion is a concept that a machine, wheel or what ever will continue in motion forever from the initial energy that is input.\n\nperpetual motion cannot exist due to the law of conservation of energy. this is because all mechanisms have some form of energy loss from friction, heat, light, radiation.\n\nthis means that no matter how efficient a machine is you will always have some energy loss somewhere and you will always have to input more energy periodically.
955164
The simplest explanation I know is in terms of the instant center.  We all think of a wheel as rotating about its axis.  That is true, relative to the tricycle frame.  However, relative to the ground, the axle moves forward.  The point where the tire touches the ground is stationary.  It does not move with respect to the ground.  An instant later, another part of the tire is touching the ground and again, for an instant, that point on the tire is stationary.  \n\nOn any rotating body, the spot that does not move (it may rotatebut not translate) is the center.  At any instant, the part of the tire touching the ground is not moving and is, by definition, the instant center.  The wheel is rotating about this instant center.  SInce the pedal is above the instant center, your forward horizontal force rotates the wheel forward.\n\nYou can prove this all to yourself by trying a few things with the string on the pedal.  Instead of pulling horizontally, raise the angle of the string.  When the line of action of the string passes through the contact point between the tire and the road, you will find that pulling on the string will not rotate the wheel.  If you pull hard enough the trike will move but the front wheel just skids.  Since the line of action of the applied force is passing through the center of rotation, there is no torque to spin the wheel.\n\nRaise the string higher and the trike will roll backwards because the force is acting on the other side of the center creating a torque in the opposite direction causing the wheel to turn the other way.   \n\nIf you don't have a trike handy, you can do this with a spool and a string.  Just wrap the string sround the spool with the end coming off the bottom of the spool.
857211
First, figure out the force the spring exerts on each block separately. (Hooke's Law) You can then find the max velocity in either of two ways, ie: using kinematics (determine deceleration of block by considering the applied forces of spring and friction by N2L), or using principle of energy conservation.\n\nI'd rather use CoE, where initial PE of spring will be converted to kinetic energy of the body + work done against friction\n\nIn equation form: 1/2 kx^2 = 1/2 mv^2 + R (uk)d, where uk = coeff of kinetic friction and R = normal contact force.\n\nHope this helps.
444300
Well try waking up in the morning. 1.the wheel rolls down an inclined plane and hits a lever. 2. the lever then triggers a pully.   i got you started now use your imagination for the rest.....
483925
You may want to try Centripedal Force i.e. Turnings and slopes..\n\nBut it has some stuff to do with Physics as well. \n\nAlso you may want to find the maximum and minumum speeds at turnings. Include Frictional Force and try to minimize it using Calculus. \n\nTake Simple Circuits like circles, oval, parabola etc. Then take their equations and use calculus to find area under the curve etc. etc.\n\nWell thatz all comes to my mind for now!! :) BEST OF LUCK..
153607
Watch skating at the Olympics tonight.  When the skater brings her arms in closer to her body, she decreases her moment of inertia.  But by Conservation of Energy, her kinetic energy must remain constant.  Her kinetic energy is given by the formula\n\nK = 1/2 I w^2  , where I is the moment of inertia and w is her (angular) rotational velocity.  If I decreases, then w must increase, i.e. she spins faster as she brings her arms in.\n\nAnother example using a more conventional rigid body: some mechanical systems, and even some experimental cars, store energy in a flywheel.  The greater the moment of inertia of the flywheel, the greater the amount of energy that is stored for a given rotational speed.
284291
If you could shoot a rocket into outer space with enough force to cause it to leave our solar system, perhaps it would exhibit "perpetual motion" and travel forever.  But that would be deceptive.  It would continue to move unchanged only because it meets little matter or force to overcome.  On earth, to set something into motion you must add to its kinetic energy which equals one half times its mass times its velocity squared.  It doesn't matter how you add the energy (or that it gains more say by falling) we are interested only in the energy you added to create perpetual motion.  It could revolve say suspended above powerful frictionless magnets within the vacuum inside an evacuated bell jar for a very long time.  However, there is no perfect vacuum on earth and there would still be atoms or molecules that would collide with and slow down the rotating item whether that took hours or days or years.  Perpetual motion must last forever(!) without you or Nature adding to its original kinetic energy.  If you hold your hand outside a moving car you will feel wind on your hand and some reasoon it could be harnessed (like a sail boat) to propel the car, neglecting the fact that the wind exists solely because the car is burning fuel.  Out of gas = out of wind.\n\nI would encourage you to pursue your theory for the lessons involved but carefully account for all the energy.  Consult with any engineer (especially mechanical at first) or any physics teacher (professor) and remember that your theory could involve a better use of energy if not perpetual motion.  You must patent most devices within a year of public disclosure (which would not include a witness to your theory or device).  Good luck.
883480
this seems an easy question but most of the student get it wrong since it is so easy to mess up your mind. it was a part of an exercise for my University exams. it makes you realise what is going on with spring ...just consider it as a opposing force. the body will drop and will expirience g --> it will accelerate. at the same time it will also expirience the sping;s opposing force.\n\nit will accelerate till the force become equal. this is the importnat factor. weight will keep on accelerating the body till it is completely cancelled by the spring force.\n\nso when \nFs = Weight then Velocity is maximum. \nso kx =mg =>\n\nx = mg / k.  (at this displacement the velocity  will be maximum)\n\nat this specigic point due to the theorem of conservation of energy we get that.\n\nkinetic energy + sping stored energy = potential energy at the start.\n\nso \n1/2mu^2 = (m*g)^2 / k => (be carefull mass = 76.7/1000kg)\nU = \n\nU = sqrt (( m*g^2)/k)) => u = 0.361m/s 9\n\nIF THE ALGBRA IS CORRECT\n\nNOW AFTER THAT POINT the body will still travel due to inertia and the springs force  larger now than gravity wll slow it down and bring it at rest \nat that point all the potential energy (due to height difference) will be transfornmed to springs stored energy therefore,\n\n1/2 k xmax^2 = mgXmax =>\n\nXmax = 2*m*g / k =>\n\nXmax = 0.02658m \n\n\n( i am at work and i believe the algebra is correct. the main point is to realise where certain things happen.)
179742
Various springs (flat or helical) deflect linearly with load and resistance of certain wires (nichrome, etc.) varies linearly with length.  If your experiment allows or expects large deflections you may be able to combine the spring/resistors into a circuit that calibrates force/deflection/resistance-reading suitable for measurement on an ohmmeter or perhaps a strip chart recorder.  Good luck.
667120
At the spring's original configuration, there is a force stretching it in the form of the mass.  The force and the amount of deflection are related through\n\nF = -kx\n\nSo the spring is stretched -F/k, or -mg/k, initially.\n\nWork to lift the weight is given by\n\nW = Fd\n\nWe have a force and a distance, so the work is then\n\nW = (mg)(-mg/k)\n= -(mg)^2/k
1005187
At its simplest, a generator involves a spinning object inside a coil, and produces electricity.  It's tempting to think that if there were no friction, that the spinning object would turn forever always generating electricity, but that's not the case.\n\nWhen energy is extracted from the generator, it is because the generator is producing a current in its coil.  This current in the coil creates a magnetic field that actually slows down the spinning object.  Friction isn't the only force slowing down the system, it's not even an important force.  The important force is this electromagnetic braking force which arises as a direct and unavoidable consequence of the extraction of energy from the generator.
870916
There is a weight mounted off-balance on a shaft so that it hangs down. It has a one-way ratchet connected to a reduction gear so that motion in one direction winds the spring. In the other direction the shaft just turns freely.\n\nAs you move about, walking, running, gesturing, whatever, your wrist moves back and forth. As your wrist changes position the weight causes the shaft to turn and the ratchet captures the motion to wind the main spring.
61932
The force of friction always opposes the motion.  \n\nWhen a force is applied to a ball or wheel, it will start rolling, provided there is a resistive force preventing the wheel from simply sliding along the other surface. The force may be a torque applied to the axle of the wheel or a linear push or pull on the wheel. The resistance of static friction causes the rolling motion. If the wheel or tire has treads and the other surface is soft, then those treads provide extra friction known as traction.\n\nNote that the friction required to start rolling motion is not rolling friction, which is defined as the friction slowing down rolling motion.\n\nAccording to the law of conservation of energy, no energy should be lost due to friction. The kinetic energy lost is transformed primarily into heat and/or motion of other objects and fluids. An airplane will heat and accelerate the air as it passes. A submarine will do the same to the water. In some cases, the "other object" to be accelerated may be the Earth. A sliding hockey puck will come to rest due to friction both by changing its energy into heat and accelerating the Earth in its direction of travel (by an immeasurable amount)