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A tippe top is a kind of
FYSIKbasen.dk
"The Tippe Top" by F.A. Bilsen
A tippe top is a kind of top
A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect.
Once set in motion, a top will usually wobble for a few ...
that when spun, will spontaneously invert itself to spin on its narrow stem. It was invented by a German nurse, Helene Sperl
Helene or Hélène may refer to: People
*Helene (given name), a Greek feminine given name
* Helen of Troy, the daughter of Zeus and Leda
*Helene, a figure in Greek mythology who was a friend of Aphrodite and helped her seduce Adonis
* Helene (A ...
in 1898.
Description
A tippe top usually has a body shaped like a truncatedsphere
A sphere () is a Geometry, geometrical object that is a solid geometry, three-dimensional analogue to a two-dimensional circle. A sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...
, with a short narrow stem attached perpendicular to the center of the flat circular surface of truncation. The stem may be used as a handle to pick up the top, and is also used to spin the top into motion.
When a tippe top is spun at a high angular velocity
In physics, angular velocity or rotational velocity ( or ), also known as angular frequency vector,(UP1) is a pseudovector representation of how fast the angular position or orientation of an object changes with time (i.e. how quickly an objec ...
, its stem slowly tilts downwards more and more until it suddenly lifts the body of the spinning top off the ground, with the stem now pointing downward. Eventually, as the top's spinning rate slows, it loses stability and eventually topples over, like an ordinary top.
At first glance the top's inversion may mistakenly seem to be a situation where the object spontaneously gains overall energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
. This is because the inversion of the top raises the object's center of mass
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...
, which means the potential energy
In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors.
Common types of potential energy include the gravitational potentia ...
has in fact increased. What causes the inversion (and the increase in potential energy) is a torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
due to surface friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of t ...
, which also decreases the kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...
of the top, so the total energy does not actually increase.
Once the top is spinning on its stem, it does ''not'' spin in the opposite direction to which its spin was initiated. For example, if the top was spun clockwise
Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite ...
, as soon as it is on its stem, it will be spinning clockwise viewed from above. This constant spin direction is due to conservation of angular momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed system ...
.
Theory
It is usually assumed that the speed of the tippe top at the point of contact with the plane is zero (i.e. there is no slippage). However, as indicated by P. Contensou, this assumption does not lead to a correct physical description of the top's motion. The unusual behavior of the top can be fully described by considering dry friction forces at the contact point.V.Ph. Zhuravlev and D.M. Klimov, On the dynamics of the Thompson top (tippe top) on the plane with real dry friction, ''Mechanics of Solids'', 40(6):117-127, 2005.See also
*Euler's Disk
Euler's Disk, invented between 1987 and 1990 by Joseph Bendik, is a trademark for a scientific educational toy. It is used to illustrate and study the dynamic system of a spinning and rolling disk on a flat or curved surface. It has been the subje ...
– Another spinning physics toy that exhibits surprising behavior
Further reading
* * * * *References
External links
FYSIKbasen.dk
"The Tippe Top" by F.A. Bilsen
Patent
* {{Patent, DE, 63261, "Wendekreisel" filed by Fräulein Helene Sperl on 07.10.1891, published on 12.07.1892" Classical mechanics Educational toys Tops Novelty items