what makes a spinning top spin

It has further to go, so it must go faster in order to get all the way around in the same time. The effect is described as precession, and is explained in simple terms below. However, if it is not spun fast enough, sliding eventually gives way to rolling, F drops to zero so the egg stops rising. Positive rake, for example, is not necessary. A tippe top not only inverts itself, it can become airborne as it does so. the Wonder of the Day via email or SMS. Thank you for providing a summary of how a toy top spins! It only takes a minute to sign up. There is an even simpler explanation. :), That's GREAT, Joe! These imperfections allow other forces, including friction and gravity, to come into play. The axis is slightly above the horizontal since the disk is spinning so fast. If it is spinning then it does something else. If you start it rotating the other way, the spoon will stop rotating and start rocking (to conserve energy) and it then starts rotating the other way. In that case, the force on the object is equal to the rate of change of its momentum. Why don't spinning tops fall over? If the pencil pivots about the bottom end, static friction prevents the bottom end from sliding. It is a super cool toy! The red particle is moving up at velocity v1 and the blue particle at the top is moving into the screen at velocity v1. How to interpret an expression when the radical doesn't extend over anything? spinning The angular momentum of the disk lies along the spin axis and points to the end supported by the string. We're so glad you joined the discussion, Jessica! First, note that it takes force to get the wheel spinning. Usually, the torque acting on a spinning top is just due to the weight of the top. Now suppose that gravity causes the top to fall to the right, as viewed from the front. Twisting the wheel about its axis would effectively pull two sides of the wheel closer to the axis of rotation of the marbles. They cover a lot of vector calculus and confuse the hell out of students without ever coming back to this simple intuitive concept. Here is a gyroscope from www.gyroscope.com Click the image to see it precess. We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature. How to fake a USB flash drive's capacity? That is the best way to measure the spin about the long axis. COMPLEJO DE 4 DEPARTAMENTOS CON POSIBILIDAD DE RENTA ANUAL, HERMOSA PROPIEDAD A LA VENTA EN PLAYAS DE ORO, CON EXCELENTE VISTA, CASA CON AMPLIO PARQUE Y PILETA A 4 CUADRAS DE RUTA 38, COMPLEJO TURISTICO EN Va. CARLOS PAZ. If spun fast enough, a spinning top will rise to a vertical position and happily stay there, despite the fact that it will fall over if it stops spinning. It will indeed fall over if it is not spinning. I thought the following post would help, but the answers would just bamboozle him I'm afraid. Friction acts in the opposite direction to motion of the bottom end. :), We're THRILLED you liked this Wonder, too, xekiel! It precesses at two different frequencies at the same time, about two different vertical axes. All existing explanations are very mathematical and quite obscure. As with a rolling ball on a horizontal surface, there is a small offset in the line of action of N, resulting in a torque that opposes the torque due to the horizontal rolling friction force. Cholera Vaccine: Dubai? First of all, I asked my son to imagine a single marble contained within a box. Others might think of action figures from an animated movie or a doll. The spin axis must move sideways instead of down, but that is just stating the observed facts in fancy technical words. spinning As it spins in its upright position, it rotates around an invisible vertical axis. Imagine a point on the wheel near the outer edge (dm1 on this diagram) and imagine you rotate the wheel to bring this point toward the top. Just like when the wheel is rotated while the pole is spinning, this creates pulls and drags on parts of the spinning top that make it want to flip over in the third direction, at 90 degrees. Tops are never perfectly balanced and weighted. When the strip rocks from one end to the other, it falls to the heavy side so the whole strip rotates in that direction. What's a reasonable environmental disaster that could be caused by a probe from Earth entering Europa's ocean? It's going too fast for the smaller circle, so it creates a 'pull' on the wheel, shown by the arrow. If the support is pushed horizontally to speed up the precession, the gyro rises vertically since the upward torque increases. The egg precesses about the Z axis due to the vertical force in the Z direction, and it precesses about the Y axis due to the horizontal force in the Y direction. That is why the top precesses by moving sideways (into the page) when it is spinning rather than falling straight down due to gravity. What happens next? The scientific forces that make it such a fun toy, however, give us a brief peek into advanced physics. craftulate We're glad you liked today's Wonder! The tippe top rotates in the opposite direction to the egg (that is, \theta increases) since the sliding friction force is in the opposite direction. You might also show him that when he spins on a desk chair, his 'speed' changes when he holds h, +1 for the bicycle wheel suggestion. So, how do you explain spinning tops to a nine year old? Why does the axis of spinning tops rotate about a vertical axis? If a small mass is located inside a hollow sphere, then the centre of mass is shifted away from the middle of the sphere. What causes certain spinning tops to flip? As it begins to wobble, the axis of the top tilts to the side, which allows the force of gravity to exert a force known as torque on the top. I might not have recorded the details of the experiment accurately but maybe the BBC archives might have a recording or may be some one could replicate the experiment, record it, and post it on YouTube? Now you have shown that spinning something in one direction and then rotating it in a second direction makes it want to flip over in a third direction, at a right angle to the other two. Pulling in different directions on the top and bottom of the wheel, makes the whole wheel want to flip over. Super cool! Other tops are spun by pulling a cord wrapped around their centers. BUT! if the top decided to fall, the spinning would either disappear or would be replaced by a totally different spinning around a horizontal axis, and Nature doesn't allow such a change of the amount of spinning to occur quickly. The other end bobs up and down rapidly due to nutation. The egg rotates initially with \Omega much larger than \omega so point P slides out of the page and the sliding friction force on the egg acts into the page. Viewed from the rear, the top falls to the left. When you think of your favorite childhood toys, what comes to mind? How can I explain or demonstrate the Lorentz Force to a 12 year old? The analogy being that you have a number and a qualifier, apples corresponds to a direction, 5 corresponds to the angular velocity. The top is spinning around a vertical axis and the spinning around this axis can't disappear. The answer you are looking for is "clockwise around an axis of rotation that is pointing up". In Feb 2014, Derek Muller repeated the experiment. 20142022 National Center for Families Learning, http://wonderopolis.org/wonder/what-makes-a-toy-top-spin, National Center for Families Learning (NCFL). Dear Peter, be sure that I agree and I know what torque is - but your comments are, in my opinion, not quite appropriate for a nine-year-old, at least not an average one. If the spinning top isn't perfectly balanced, if it leans slightly in one direction, gravity will try to pull it over in that direction. That friction force acts to rotate the spoon in the direction you see it rotating, even if there is no rotation at the start. @Lubos I have no idea, perhaps I promote Russian because I'm unfamiliar with Czech :D . G rises since the top precesses about the Y axis due to the friction force in the Y direction. I then asked him to guess what might happen to the marble if the box was pushed in a straight line from left to right. It's GREAT when we're learning and having fun! How is Number Of Confirmations derived for a transaction? The third and fourth is the same disk supported on a round, brass knob. +1 I like the last paragraph. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Its so fun It drops below the horizontal as it slows down. SCIENCE Physical Science. All are described by Eulers angular momentum equation which relates the change in angular momentum to the torque on the object. So when gravity makes the top lean over one way, the flipping effect tries to make it lean over in a different direction. origami Hi, Xander! First you need to explain how the speed of points on a spinning object changes with distance from the axis of rotation. tower tops spinning I would like to add another explanation that is probably at the 9-year-old level. What would the term for pomegranate orchard be in latin or ancient greek? However, if it is not spun fast enough, sliding eventually gives way to rolling. Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Connect and share knowledge within a single location that is structured and easy to search. At one point near the beginning, the spoon actually slides on the table, but mostly it doesnt because static friction prevents it sliding. The way the wheel is spinning means the the circle the dot makes as it gets nearer the top must get smaller, so that part of the wheel has to slow down. Be the first to know! Then note that it takes force to stop it from spinning. The egg therefore rises. The circle made by this part of the wheel is getting bigger, so this part of the wheel has to speed up. A rattleback not only slows down to a stop but it then reverses direction. @Qmechanic Actually the first is not outlandish, as in my experience volunteering at my daughter's primary school "science room", when you try to explain these ideas with a bicycle wheel, precession is the first thing small children almost universally notice after they notice that the wheel doesn't fall over. One has to have a torque to change the amount of spinning, some force attempting to change the rotation, but the torque acting on the bottom tip of the top is so small that with a fast enough initial spinning, it takes a lot of time to change the spin substantially. The angular momentum vector L points along the spin axis and rises slowly as the top rises. Copyright 2022 ec Estudio Integral. You might need to draw a picture or use a model to convey this. The wood egg was spun faster and stood up higher. As long as the top keeps spinning, the flipping effect means it can't fall over! How to explain gyroscopic precession in a more intuitional way? But a torque, as something different than force, is tougher. If you don't already have one at home, try to purchase one to take home to play with, so you can see the physical forces you learned about in action. When it's spinning, a top balances on a tiny tip. cd spinning tops Whether you spin the top with your fingers or hold the top upright while you pull a string to start it spinning, the top spins rapidly, miraculously staying upright for a long time before eventually beginning to wobble and finally fall back onto its side. The result is that the direction in which the top leans constantly changes - it is pulled around in a circle! But as for the rest, check out the idea of a. spinning tops metal toys fidget lathe precision spinny doo cnc edc spinner makes spin cool projects spinners toy takes put How can I get an AnyDice conditional to convert a sequence to a boolean? The two dots must do the same number of turns per second around the middle, but the outer dot travels in a bigger circle. The egg has more potential energy when the fat end is at the top, so there is more kinetic energy when it falls. How do you explain spinning tops to a nine year old? What is the source for C.S. Nevertheless, there is a simple explanation, and it involves the effect of friction. All four objects here are spinning on a horizontal surface, all precess at angular velocity \Omega about a vertical axis (Z) through the centre of mass (G), and all spin at angular velocity \omega about an axis of symmetry. Some tops are released from about hip level with a snap of the wrist and sent spinning to the floor. Any object that is moving at high speed left to right will continue moving left to right due its momentum, although it can also move up or down if an up or down force is exerted while it is moving. When it's spinning, you have the linear momentum AND the angular momentum resisting gravity. Now imagine the pole is spinning the whole wheel around the vertical axis, similar to a spinning top. Closest equivalent to the Chinese jocular use of (occupational disease): job creates habits that manifest inappropriately outside work. Why are my cantilever brake pads already on rim without pulling brake lever? Without getting into advanced physics and mathematics, let's take a look at some of the basic forces that make a top spin. Asking the child if they can identify if anything is actually touching the spinning top. I'm trying to figure out how to relate things to a 9-year old, and I think things can be conveyed more simply by describing everything in terms of force (which is something he can feel). Here is another explanation. In this case, however, I'm stumped. (Showing that the angular momentum was zero!). It still looks like magic, especially since the film is viewed in slow motion and the disk seems to be rotating at low speed. How did Wanda learn of America Chavez and her powers? Imagine the top from, well the top. Now, look carefully at the video. It spins for a long time. spinning diy IDEAL OPORTUNIDAD DE INVERSION, CODIGO 4803 OPORTUNIDAD!! And vice-versa if the disk rotates downwards. What happens if a debt is denominated in something that does not have a clear value? Thanks for your patience. The same thing would happen if you tried to balance a pencil on one end on the table and tilted it sideways slightly so that it falls. That is simply amazing. In order to understand the behaviour of a spinning egg, it is necessary to understand the effect of the forces on the egg. In the video I started the spoon rocking by pushing down on one end and then releasing the spoon. How many different kinds can you find? wheel spinning circle toy craft cardboard crafts toys teens artistshelpingchildren children making lesson projects create The wheel is mounted vertically and can rotate around a horizontal axis, in addition the pole can spin the wheel around a vertical axis. The two dashed lines represent the components of the velocity vector one parallel to the edge of the disk and one perpendicular, showing the front edge lifting up. Along time ago (1960's) I saw on TV a show where a scientist was explaining the working of a spinning top in front of an audience of children. See Eur J Phys Dec 2017. Imagine (or better, draw!) There is nothing magic about that. Tell everybody about Wonderopolis and its wonders. If you spin an object on a table, then friction will slow it down until it comes to a stop. I filmed the Herculian effort at 300 fps. Lets be practical and think with the mind of 9 year old, this is my approach: Tell him to stretch his arms and start spinning and now tell him to fold his arms and start spinning again (make sure he doesnt do it vigorously ) and now ask his observation saying which one was easy and say the same feeling would have been to the spinning top if it could think , you can then show his feet (compare with the tops axial) and say you are able to spin without falling as you are maintaining your position and speed relative to this point, Hope this will clear your child's doubt :). Conclude by asking them the leading question "If nothing is touching or bothering the top, why would the amount of spinning change?". There was no rotation at the start. It precesses once in 1400 frames or in 1400/600 = 2.3 seconds so it precesses at 0.43 Hz or 26 rpm. We're glad you liked this Wonder! It turns itself completely upside down and ends up spinning with its peg underneath the sphere that was originally spinning underneath the peg used to spin it. Purely mechanical description of how gravity causes a gyroscope to precess, Physics of the point of contact for a spinning top, Torque and angular acceleration with bicycle wheel. EXCELENTE OPORTUNIDAD DEPARTAMENTO CNTRICO EN COSQUIN, OPORTUNIDAD CHALET VILLA MIRADOR DEL LAGO. Looking from a child's pov, if you place a top on it's point, it will fall over because it isn't perfectly balanced. A gyroscope is not actually self-stable: perturb it and it by default preserves the perturbation. The effect of the torque is to create additional spin while also causing the top to precess (swing) outward. Moreover, the surfaces they spin on aren't perfectly level either. Of course energy is used every time the top must lift itself, so it eventually slows down and crashes. ? The secret of a rattleback is that the distribution of mass is not lined up with the geometric axis. How do I explain why a spinning top doesn't fall down without going into the mathematics of angular momentum? The scientist spun the wheel and rotated the roundabout. One strategy to reduce the mental load is to use a higher order concept such as. If the top is perfectly upright there is no torque acting on it but if it leans sideways then it will tend to fall over due to the torque about the bottom end. 3 If you add up these two independent movements, you find that the the vertical movements (turning up, falling down) have cancelled out, so that its net movement is more akin to rolling. trick tricks spinning keys ta0 Leading questions like "what is the top spinning about?" Stuff falls over because the earth's gravity acts on it with a force to pull it down. The bottom end of the pencil would either slide on the table or pivot about the bottom end, depending on the coefficient of friction. If you look carefully you will see that the spoon rocks from side to side and from end to end while it rotates. I cant remember what the mathematics was behind this but I knew the boy could easily move the heavy bar up and down. G rises since the top precesses about the Y axis due to the friction force in the Y direction. If the wheel spins, the gyro generates an upward torque to balance the counter-weight, and the gyro precesses slowly. In any case, the potential energy within the top is released, changing to kinetic energy, the energy of movement and motion. If the wheel is not spinning then the counter-balance at the opposite end is not heavy enough to hold the wheel up. A simple explanation of precession can be given in terms of the diagrams below. The spinning top is spinning about its vertical axis, like the wheel being spun around by the pole. It comes in a wide variety of shapes and colors, but its function remains the same across varieties. Pretty sure the child's confusion is that why should, I liked you Russian phrase. spinning stl file 3d So a good explanation would put the two together. The way the wheel is being spun by the pole means that the left half and the right half of the wheel are moving in opposite directions, so a pull on one side and a drag on the other are in the same direction. However, all tops eventually fall when the spin drops to a low value. If you look carefully, you will see that the egg spins slowly about its long axis. Point out that it takes force to get it moving and to stop it moving. Thanks for sharing all the GREAT info, Garcia! The left end is supported by a length of string. A tippe top does something similar, but is even more spectacular. The basic physics behind all these effects is that a torque is required to rotate an object.

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