Imagine the top from, well the top. Copyright 2022 ec Estudio Integral. 
However, if it is not spun fast enough, sliding eventually
gives way to rolling. It is a super cool toy! Asking the child if they can identify if anything is actually touching the spinning top. Momentum as an english term is somewhat abstract, imho. Presumably they will come up with something akin to angular velocity, the number of rotations in some time, etc. Angular momentum is similar to linear momentum,
but it refers to motion in a circular rather than a straight line path. See also Spinning eggs and
ballerinas, Physics Education, 48(1), 51-56 (2013). The first two are a 100 gram aluminium disk with a
pointy bottom end, viewed from the side and the top (just before it fell). If you ask the same question of older adults, such as grandparents, you'll probably hear about a variety of simpler types of toys. A spinning egg is just as amazing. In
the video I started the spoon rocking by pushing down on one end and then
releasing the spoon. Is it permissible to walk along a taxiway at an uncontrolled airport to reach airport facilities? I love wonderopolis, for an unlimited or unspecified period of time, in a manner highly improbable and extraordinary and bringing very welcome consequences, relatively long in duration; tediously protracted, a statement or account that makes something clear, something regarded with special favor or liking, the center around which something rotates, a series with a definite pattern of advance, the outer boundary of an artifact or a material layer constituting or resembling such a boundary, http://www.byron.com/topbook/history.html, http://www.ehow.com/how-does_4964211_spinning-top-work.html, http://www.livescience.com/33614-the-cool-physics-of-7-toys.html. That is simply amazing. 
If you're Jewish or have a Jewish friend, then chances are you've probably seen or played this fun game that features small objects similar to a spinning top. 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. Why are my cantilever brake pads already on rim without pulling brake lever? My answer is much that same as to why one can easily balance on a typical bicycle. Eventually, though, friction will begin to slow the top's spin. My nine year old son asked me this very question when playing with his "Battle Strikers" set. Your 9-year old son? The
usual tippe top has a peg on top to spin it, and its centre of mass is located
below the centre of curvature. Dont miss our special deals, gifts and promotions. The boy held a metal bar with a wheel on its end (Quite heavy!) If the fat end remains at the
bottom after falling, then the thin end can rotate all the way up to the top
with enough energy left over to swing it past the top. 
First, you want to get him familiar with the idea of linear momentum. 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. Did today's Wonder of the Day leave your head spinning? The circle made by this part of the wheel is getting bigger, so this part of the wheel has to speed up. I'm going to take a stab at this! 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. We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature. ;-), As we know: we have the difficulty that the motion cannot even be simplified to 2-dimensional motion; gyroscopic precession is irreducibly motion in all three spatial dimensions. The
egg therefore rises. I told him that scientists like to call this inertia. As the top's spin continues to slow, it precesses faster in an attempt to conserve its total angular momentum. The torque is due to the string pulling up on the axle and it acts in a
direction into the screen. While precession depends on the conservation of angular momentum, I think this explanation makes it clear what's going on kinematically, without relying on concepts that are hard to develop at that age. :), We're THRILLED you liked this Wonder, too, xekiel! But most surprisingly the scientist put up a tick in front of the bar and roundabout stopped immediately. A pair of forces is OK for a nine-year-old.
At one point near the beginning, the spoon actually slides on the table, but
mostly it doesnt because static friction prevents it sliding. OK, I'll give it a shot. The outward force of the marbles away from their central axis of rotation would resist this change, thereby causing a resistance to the twisting action on the axis of the wheel. Most tops are put into motion by twisting the top stem with a snap and releasing. Careful not to catch your nose on the spinning tyre though! The secret of a rattleback is that the
distribution of mass is not lined up with the geometric axis. They probably have fond memories of slingshots, rubber balls, and battles between groups of tiny green Army men. How can I explain or demonstrate the Lorentz Force to a 12 year old? That is why
the top precesses by moving sideways (into the page) when it is spinning rather
than falling straight down due to gravity. So the top is pulled in two new directions, and the direction it leans changes again. (c) 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. Here is a spinning hollow plastic
egg, a solid wood egg and a solid aluminum egg. Pretty sure the child's confusion is that why should, I liked you Russian phrase. SCIENCE Physical Science. 20142022 National Center for Families Learning, http://wonderopolis.org/wonder/what-makes-a-toy-top-spin, National Center for Families Learning (NCFL). @Lubos I have no idea, perhaps I promote Russian because I'm unfamiliar with Czech :D . This minimizes the amount of friction generated by its contact with the surface below it. Any object weighted on one side will tend to fall to that side
when it is allowed to fall. EXCELENTE OPORTUNIDAD DEPARTAMENTO CNTRICO EN COSQUIN, OPORTUNIDAD CHALET VILLA MIRADOR DEL LAGO. Leading questions like "what is the top spinning about?" 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. The answer you are looking for is "clockwise around an axis of rotation that is pointing up". 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.
Closest equivalent to the Chinese jocular use of (occupational disease): job creates habits that manifest inappropriately outside work. Then I asked him what would happen to the marble if the moving box suddenly stopped. 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. It's a great way to get the point across in a way that can really be seen, and felt. We're so glad you joined the discussion, Jessica!
If
you look carefully, you will see that the egg spins slowly about its long axis. Further details can be found in The rise
and fall of spinning tops, Am J Phys 81(4), 280-289 (2013). Similarly, the momentum of the
blue dot tends to carry it forward in a straight line. This is probably the hardest part to explain. If you don't have a dolly with rotatable wheels, you can probably improvise something along these lines. The analogy being that you have a number and a qualifier, apples corresponds to a direction, 5 corresponds to the angular velocity. Pulling in different directions on the top and bottom of the wheel, makes the whole wheel want to flip over. The usual explanation is
that the change in angular momentum must be in the same direction as the torque
on the top that is, in the sideways direction. But as for the rest, check out the idea of a. There is nothing magic about that. You will see the tops spinning ten times slower
than they actually did. 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. You can watch it for as long as
you like, and it wont fall down. Why does the axis of spinning tops rotate about a vertical axis? Cholera Vaccine: Dubai? 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. Then, have him push you around in a circle (or an arc), so he can understand that it takes force to change the direction something is moving in. Here is a gyroscope from www.gyroscope.com Click the image to see it precess. This is a pretty nice yet simple toy in various science museums, including "Techmania" we have here in Pilsen. 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. It looks like a magic
trick with a hidden spider thread holding up the other end. Presumably their intuition will jump to clockwise and counterclockwise. After a theoretical discussion it is good to have a physical demonstration - Lubos's suggestion of using a bycicle wheel is perhaps the easiest way to demonstrate the fact that "things want to keep spinning the same direction* in a way that the child can feel.
The best answers are voted up and rise to the top, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company. 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. :), That's WONDERful, Rose! We sent you SMS, for complete subscription please reply. Disregarding the term moment you can describe angular momentum (and linear momentum) as an amount of motion, since quantities of things is something a 9 year old should be fairly familiar with, I propose pivoting explanations around this interpretation. +1 I like the last paragraph. Point out that it takes force to get it moving and to stop it moving. 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. Spun slowly clockwise, the egg
precesses in a counter-clockwise direction, rocking from one end to the other, in the same way that
people move heavy furniture. Now you can try to explain the gyroscope using these two principles that the kid understands. YouTube videos of the experiment can be found at http://youtu.be/GeyDf4ooPdo
and http://youtu.be/tLMpdBjA2SU. If the disk rotated down the screen the two Fs
would generate a torque about the vertical axis. But I've noticed that the simple concept that momentum represents an amount of motion is underemphasized in U.S. introductory physics courses. I attached a thin wire to the spoon, along its axis, to see
the motion more clearly. The other end bobs up and down rapidly due to
nutation. Here is a simple gyroscope filmed
at 600 frames/sec. The brass end top takes a while to stand up
straight, as shown in the fourth video clip. I would like to add another explanation that is probably at the 9-year-old level. ? 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. I then asked him to imagine a set of boxes, each containing a marble, attached to the circumference of a wheel. Tops are never perfectly balanced and weighted. It precesses at two different frequencies at the same
time, about two different vertical axes. Ask the child if 5 apples can become 5 oranges magically. I used two small pieces a Blu-Tack, a
re-usable adhesive. For that reason, a tippe top stands upright when
placed at rest on a horizontal surface.
Bicycles will actually correct such perturbations. What is the purpose of overlapping windows in acoustic signal processing? How do you explain spinning tops to a nine year old? :). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. When this occurs, the top begins to wobble, demonstrating a scientific principle called precession. Besides, some adults DO play with
spinning tops (check the web), and some make very elegant ones (see www.puccimanuli.com under spinners). The string swings out from the vertical to provide a centripetal
force on the gyro since the gyro rotates slowly in a circular path about the
vertical axis.
On its pointy end, the egg rolls right over then
slides. The torque is equal
to the rate of change of angular momentum. The egg is sliding
rather than rolling on the horizontal surface in this case so there is a relatively
large friction force on the egg. Lote en Mirador del Lago:3.654 m2.Excelente vista al Lago, LOTE EN EL CONDADO DE 1430 m2, EN COSQUIN.
It has further to go, so it must go faster in order to get all the way around in the same time. looking down on the spinning top from above, when it is spinning perfectly balanced.
The top is spinning around a vertical axis and the spinning around this axis can't disappear. The left end is supported by a length of string.
If the top were perfect in every way -- perfectly balanced and weighted -- and the floor was perfectly level as well, the top would rotate pretty much indefinitely. Conclude by asking them the leading question "If nothing is touching or bothering the top, why would the amount of spinning change?". For further details, see
Spherical Tippe Tops in The Physics Teacher, 51(3), 144-145 (2013). Undefined behavior (according to clang -fsanitize=integer) on libstdc++ std::random due to negative index on Mersenne Twister engine, Convert all small words (2-3 characters) to upper case with awk or sed. Be sure to check out the following activities with a friend or family member: The way the top spins around the rotation axis gives it angular momentum, and the angular momentum will remain constant until an external source of torque acts on the spinning top. For example, a bullet fired horizontally will continue to move at high speed in
a horizontal direction while it falls slowly to the ground under the influence
of the vertical gravitational force. With steady precession, there is no falling motion
at all. First you need to explain how the speed of points on a spinning object changes with distance from the axis of rotation.
Thats the amazing part. The change in v is directed left to right in
each case, as shown in the diagrams below, so there must be a left to right
force F on the particle to change its velocity. When it's spinning, a top balances on a tiny tip. Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Elementary explanation for motion of a gyroscope, Explaining to a five year old - why don't bubbles run like water. As a result, the rear
edge of the top tilts down. Now imagine the pole is spinning the whole wheel around the vertical axis, similar to a spinning top. Viewed from the rear, the top falls to the
left. (Showing that the angular momentum was zero!). Its centre of mass rises slowly
since the brass ball rolls and the friction force at the bottom end is
relatively small. It precesses once in 1400 frames or in
1400/600 = 2.3 seconds so it precesses at 0.43 Hz or 26 rpm. The disk acts a gyroscope and precesses in a
horizontal plane rather than falling vertically. The wheel is mounted vertically and can rotate around a horizontal axis, in addition the pole can spin the wheel around a vertical axis. Can you find any spinning tops? See Eur J Phys Jan 2018. Having studied Physics myself, I am very keen to encourage him to take an interest in Science and I am delighted when he asks me such questions. When a spinning top starts to wobble and then falls over, that is because torque starts to pull on the bottom of the top as its spinning slows. Want to add a little wonder to your website? Well, the angular momentum conservation is still the essence although it may be formulated in a different language. The direction of the roll is such as to move the bottom of the top back underneath its center of gravity. IDEAL OPORTUNIDAD DE INVERSION, CODIGO 4803 OPORTUNIDAD!! Vancouver? This may actually confuse the child. If a hard-boiled egg is spun fast enough it will rise up and spin on one end. Some toys have a spinning gear that is activated by pulling a plastic, toothed strip through it to launch the top. How can I get an AnyDice conditional to convert a sequence to a boolean? Math Proofs - why are they important and how are they useful? In 1974, Professor Eric Laithwaite
showed that he could lift an 18 kg disk above his head, using one hand, when
the disk was spinning on the end of a 0.9 m long axle. Of course this is not a complete description by any means, and misses a lot of the extremely important details (like precession), but c'est la vie. It is the rotational equivalent of what happens when an object accelerates
along a straight line. So when gravity makes the top lean over one way, the flipping effect tries to make it lean over in a different direction. How to interpret an expression when the radical doesn't extend over anything? How do people live in bunkers & not go crazy with boredom? But most tops aren't perfect and will begin to lose their momentum. See Eur J Phys Dec 2017. How is Number Of Confirmations derived for a transaction? If the pencil pivots
about the bottom end, static friction prevents the bottom end from sliding. Compared to modern toys, the spinning top may seem quite simple. ;-) You must be from a nation South from mine, right? When it's spinning, you have the linear momentum AND the angular momentum resisting gravity. This time I asked him to guess what might happen to the marbles in each box when the wheel started spinning, when it remained spinning at a constant speed and finally when the wheel stopped spinning. Suppose the mass begins to tip to the right. 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. It is smaller than the spin about the vertical axis. It still looks
like magic, especially since the film is viewed in slow motion and the disk
seems to be rotating at low speed. Here's the clever part! The scientist spun the wheel and rotated the roundabout. Junior employee has made really slow progress. Because the spin axis must fall sideways, the torque makes the top fall sideways rather than straight down. Positive rake, for example, is not necessary. If it is spinning then it does something else. How do I explain why a spinning top doesn't fall down without going into the mathematics of angular momentum? A
tippe top does something similar, but is even more spectacular. So a good explanation would put the two together. That is the best way to measure the spin about the long
axis. Every time gravity tries to pull the top over one way, the flipping effect makes it lean a different way. The red dot on the front edge represents a small part of the top, and it
is moving left to right at high speed. Brass disk on P800
emery paper
at 300 fps. 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. The mass of the brass disk is 108
grams, and its diameter is 56 mm. Announcing the Stacks Editor Beta release! How many different kinds can you find? The effect is shown in the
following slow motion video clip. And that's why it takes longer to fall over. Bangalore? I cant remember what the mathematics was behind this but I knew the boy could easily move the heavy bar up and down. Moreover, energy conservation guarantees that if there's no friction, the top can't ever fall. G
rises since the top precesses about the Y axis due to the friction force in the
Y direction. When a spinning top starts to tilt, the point in contact with the supporting surface shifts away from the axis causing the top to roll. 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. Connect and share knowledge within a single location that is structured and easy to search. the Wonder of the Day via email or SMS. If you've ever played with a spinning top, you can see how fun it would be to spin an acorn in a similar way. @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.
Explaining Newton's Laws of motion to a 6 year old. Nevertheless, there is a simple explanation, and it involves the
effect of friction. The disk rotates once every 10 frames or in 10/600 seconds,
so it spins at 60 Hz or 3600 rpm. A horizontal force
applied to increase the precession frequency would cause the disk to rise. The egg has more potential energy when the fat end is at the top, so
there is more kinetic energy when it falls. Next, to explain how two different rotations create a third rotation. Check out the position of the dot on the pointy end each time the pointy end
points to the camera. However, that is not the case. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. It precesses quickly about a vertical axis through the middle of the egg
and precesses slowly about a vertical axis located outside the egg. Dr. Motl's suggestion of a bicycle wheel is a good one. :), Hi, Dylan! Then note that it takes force to stop it from spinning. If the wheel spins, the gyro generates an upward torque to
balance the counter-weight, and the gyro precesses slowly. These imperfections allow other forces, including friction and gravity, to come into play. When the spoon tilts sideways, it tends to slip
sideways on the the table. Now suppose that gravity causes the top to fall to
the right, as viewed from the front. To be honest: I know of angular momentum conservation, but nevertheless every time I play with such a top it is a wonder/riddle to me again. 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. There is an even simpler
explanation. 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). Without getting into advanced physics and mathematics, let's take a look at some of the basic forces that make a top spin. To learn more, check out. The top is steadied and rests with its bottom tip touching the floor. The bottom
end makes a big difference. 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. Now you can show the same thing for points on the bottom half of the wheel, except that the pull and the drag on the bottom half are in the opposite direction to those on the top half. Mhhhhm, do You know it Yourself? See also e.g. Imagine a wheel mounted on a pole, like this diagram from wikipedia: http://upload.wikimedia.org/wikipedia/commons. So, the two small
masses must be located as shown in this 3Mb QuickTime slow
motion video taken at 300 fps. There are many theoretical
papers on the subject and many videos of rattlebacks on YouTube, but there are
no simple explanations. This rotates the top in that direction. 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. The spinning top is spinning about its vertical axis, like the wheel being spun around by the pole. 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. For an object that's not spinning, all it has is the linear momentum resisting gravity. What is the source for C.S. See also this page which contains the picture above as well as some other insightful games and experiments relevant for the angular momentum. It sounds like you know a lot about toy tops. Interested in sharing Wonderopolis every day? You can make
your own rattleback by cutting the handle off a plastic spoon and attaching two
small masses to each end of the spoon.
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