This most attractive example is in the apparatus collection at Bowdoin College. It has no maker’s name and is about 40 cm high.
The gyroscope was invented in 1852 by the French experimental physicist Leon Foucault (1819-1868) as part of a two-pronged investigation of the rotation of the earth. The better-known demonstration of the Foucault pendulum showed that the plane of rotation of a freely-swinging pendulum rotated with a period that depends on the latitude of its location.
His gyroscope was a rapidly rotating disk with a heavy rim, mounted in low-friction gimbals. As the earth rotated beneath the gyroscope, it would maintain its orientation in space. This proved to be hard to do in practice because the frictional forces bring the spinning system to rest before the effect could be observed. The gimbal bearings also introduce unwanted torque. But, the principle is well-known to all children who move their toy gyroscopes about and observe that the spinning disk stays in the same orientation. Continue reading
How Gyroscopes Work
by M. Brain
Gyroscopes can be very perplexing objects because they move in peculiar ways and even seem to defy gravity. These special properties make gyroscopes extremely important in everything from your bicycle to the advanced navigation system on the space shuttle. A typical airplane uses about a dozen gyroscopes in everything from its compass to its autopilot. The Russian Mir space station used 11 gyroscopes to keep its orientation to the sun, and the Hubble Space Telescope has a batch of navigational gyros as well. Gyroscopic effects are also central to things like yo-yos and Frisbees!
If you have ever played with toy gyroscopes, you know that they can perform all sorts of interesting tricks. They can balance on string or a finger; they can resist motion about the spin axis in very odd ways; but the most interesting effect is called precession. This is the gravity-defying part of a gyroscope. Continue reading
In physics, torque can be thought of informally as “rotational force”. The concept of torque, also called moment or couple, originated with the work of Archimedes on levers. The force applied to a lever, multiplied by its distance from the lever’s fulcrum, is the torque. Torque is measured in units of newton metres, and its symbol is τ.
For example, a force of three newtons applied two metres from the fulcrum exerts the same torque as one newton applied six metres from the fulcrum. This assumes the force is in a direction at right angles to the straight lever. More generally, one may define torque as the cross product:
F is the vector of force.
r is the vector from the axis of rotation to the point on which the force is acting.
The rotational analogues of force, mass and acceleration are torque, moment of inertia and angular acceleration respectively. Continue reading
Guardian of the Horizon
By Andrew Bayuk
The Sphinx of Giza [Her-em-Akhet] is a symbol that has represented the essence of Egypt for thousands of years. Even with all of the pictures that we see of the Sphinx, nothing can really prepare you for the time that you finally see the Sphinx with your own eyes. Here’s a look at the Sphinx that will give you a hint of what you can expect to see if you visit Egypt.
Carved from the bedrock of the Giza plateau, the Sphinx is truly a mysterious marvel from the days of ancient Egypt. The body of a lion with the head of a king or god, the sphinx has come to symbolize strength and wisdom. Continue reading
The Mystery of the Great Sphinx
By Brian Haughton, 2011 [Edited]
Buried for most of its life in the desert sand, an air of mystery has always surrounded the Great Sphinx, causing speculation about its age and purpose, method of construction, concealed chambers, role in prophecy, and relationship to the equally mysterious pyramids. Much of this theorizing is to the despair of Egyptologists and archaeologists.
The Mystery of the Great Sphinx
Facing the rising sun, the Great Sphinx is located on the Giza plateau, about 10 km west of Cairo, on the west bank of the Nile River. Later Egyptian rulers worshipped it as an aspect of the sun god, calling it Her-Em-Akhet (“Horus of the Horizon”). The Sphinx sits in part of the necropolis of ancient Memphis, the seat of power for the pharaohs, a short distance from three large pyramids – the Great Pyramid of Khufu (Cheops), Khafre (Chephren) and Menkaura (Mycerinus). Continue reading