Why spinning top does not collapse

Absolutely, that is what you should expect to happen. And it does The final solution is a little more involved than just being uniform rotation around the vertical axis. Keep in mind, however, that the top is now rotating around two different axes. Let's see how this happens. This is true for all but the most oddly shaped tops. Convince yourself that this is the case. In circuits more current flows through paths with lower resistance.

Likewise in mechanics more energy is transferred to the component with lesser inertia. Now, conservation of angular momentum requires that there be a torque corresponding to this increase. The effect of this induced torque is to cause the falling top to start swinging back upwards. In this way, instead of a spiral, the tip of the top traces out something like a cycloid as it precesses around the central axis.

I would not have known of this rather elaborate dynamics if not for one of Feynman's lecture volumes Part I, I think where this question is considered in great detail! The above write-up is a little on the hand-wavy side and there probably are errors in my reasoning. For the full kahuna look up the Feynman lectures! When it is spinning its angular momentum is quite high. By conservation of angular momentum the spinning top is then more stable against small torques like the action of gravity on the top.

You can find a detailed discussion on this page of Hyperphysics. All the explanations given involve conservation of angular momentum, which is perfectly correct, but I feel that people with no thorough background in physics and mathematics will be left unsatisfied with this. Is there a way to explain conservation of angular momentum in terms which would be understandable to the layman?

It's a pedagogical problem I have given a lot of thought and I have yet to find a satisfactory answer. Surely, you need to start from something, some basic axiom that the person will be willing to accept at face value. I thought about using either the law of action and reaction or conservation of momentum. I think these are relatively easy to describe "pictorially". But going from these to angular momentum using a vector product, is a mathematical procedure I'm not sure I can explain to someone who doesn't know anything about math.

So, this should be circumvented in some way by a nice visual example again to make things clearer and I haven't found one. The point is that conservation principles are not generally intuitive. For example, why should energy be conserved?

One must have a grip of the dynamics involved in order to understand them. Anyway, the precession of the spinning top doesn't have to do with the conservation of angular momentum. It has to do with the strange nature of torque and its interaction with angular momentum. When a force acts on a spinning top, it excerpts a torque perpendicular to the plane defined by the axis of the top and the direction of gravity, which is a vertical plane.

Answer gravy : The quick and dirty physics explanation is: Angular momentum is conserved and, like regular momentum, that conservation takes the form of both a quantity and a direction.

For example, with regular momentum, two identical cars traveling at 60mph west have equal momentum, but if one of those two identical cars is traveling east at 60mph and the other is traveling west at 60mph, then their momentum is definitely not equal. For example, the hands on a clock are spinning, and their angular momentum points into the face of the clock.

So, in a cheating nutshell, tops stay upright because falling over violates angular momentum. Of course, it will eventually fall over due to torque and friction. The torque from gravity creates a greater and greater component of angular momentum pointing horizontally, and the friction slows the top and decreases the vertical component of its angular momentum.

Once the angular momentum vector which points along the axis of rotation is horizontal enough the sides of the top will physically touch the ground. Essentially, tops prefer to spin on a very particular axis, which makes the whole situation much easier to think about.

However, for centuries creative top makes have been making tops with very strange moments of inertia that causes the tops to flip or drift between preferred axises, which makes for a pretty happening 18th century party. Both momentum and angular momentum are vector quantities, that is they both have magnitude and direction. You said only angular momentum was a vector.

If you have a top with a motor turning it at constant speed mounted on a cylinder, it will force itself upright…correct? Now in the same scenario, you have a servo mounted on the cylinder and its shaft is parallel to the cylinder. Its purpose is to rotate the mount of the top. If the servo turns the mount for the top 45 degrees in either direction, the top will try to keep its upright position?

Does this mean that the entire assembly will now be at that 45 degree angle without falling over? If so, will the top force the entire assembly to move in any direction parallel with the ground?

A top shall begin to wobble as it loses mechanical, or kinetic.. If a top is perfectly balanced.. A tippe top does something similar, but is even more spectacular. 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.

The basic physics behind all these effects is that a torque is required to rotate an object. The torque is equal to the rate of change of angular momentum. There is nothing magic about that. It is the rotational equivalent of what happens when an object accelerates along a straight line.

In that case, the force on the object is equal to the rate of change of its momentum. Angular momentum is similar to linear momentum, but it refers to motion in a circular rather than a straight line path. Usually, the torque acting on a spinning top is just due to the weight of the top. 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.

It will indeed fall over if it is not spinning. If it is spinning then it does something else. The effect is described as precession, and is explained in simple terms below. A spinning top precesses slowly around a vertical axis through its point of support while it spins rapidly about its own axis. The spin axis must move sideways instead of down, but that is just stating the observed facts in fancy technical words.

The following slow motion video clips show what happens with different types of tops, including a spinning egg and two types of tippe top. The tops were filmed at fps to measure their spin and rate of precession.

You will see the tops spinning ten times slower than they actually did. The first two are a gram aluminium disk with a pointy bottom end, viewed from the side and the top just before it fell.

The third and fourth is the same disk supported on a round, brass knob. The bottom end makes a big difference. The brass end top takes a while to stand up straight, as shown in the fourth video clip.

Its centre of mass rises slowly since the brass ball rolls and the friction force at the bottom end is relatively small. It is the torque generated by friction at the bottom end that causes tops to rise upward and defy gravity. However, all tops eventually fall when the spin drops to a low value. Here is a spinning hollow plastic egg, a solid wood egg and a solid aluminum egg.

It precesses at two different frequencies at the same time, about two different vertical axes. It precesses quickly about a vertical axis through the middle of the egg and precesses slowly about a vertical axis located outside the egg.

The wood egg was spun faster and stood up higher. All three eggs rise as a result of sliding friction until they start rolling and then the precession frequency is about the same as the spin frequency — unlike a sharply pointed top where the precession frequency is much smaller than the spin frequency. In order to understand the behaviour of a spinning egg, it is necessary to understand the effect of the forces on the egg.

Here are three more slow motion video clips showing what happens when an egg falls from rest and when an egg is spun very slowly. The only forces on the egg are gravity, the normal reaction force and friction, but all three videos contain some surprises.

If an egg is on its fat end when it falls, it slides forward. On its pointy end, the egg rolls right over then slides. The egg has more potential energy when the fat end is at the top, so there is more kinetic energy when it falls. There's an important result from all of this - you get slower precession if the spin is fast or if the couple is small.

This is because the smaller the couple, or the larger the spin angular momentum then the change in spin direction red arrow is smaller.

The moon, for example, goes around the Earth at constant speed, but its' direction of travel is changing continuously due to the force of the Earth's gravity.

See other gyro links here. Explanation B less technical : What stops a spinning top from falling over? All we need to show is that the force of gravity is insufficient to cause the top to fall.

The only force acting to push the top over is gravity. First think what happens when the top is not spinning. It falls over and we get a feel for how long it takes for the top to fall and how fast it is going when it falls. This gives us a feel for how much angular motion that gravity alone can give to the top if it were to fall over. Let's call this angular motion "spin", but note that gravity can only create "spin" about a horizontal axis.