Galileo Galilei Exhibition Gallery
Telescope
Galileo's was the first scientist to use the telescope to observe and describe the phases of the moon, the solar spots, four satellites of Jupiter (giving them Italian names: Io, Europa, Ganymede and Callisto) and even the rings of Saturn.
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Hydrostatic balance
Galileo invented a method to calculate the specific mass density of objects by resuming the studies begun by Archimedes on floating bodies. He improved it by attaching a scales system that measures the hydrostatic thrust (force) caused by the water displaced by body inserted in the water.
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Archipendulum
The Archipendulum (whose name is composed of the words Arc and Pendulum) is a simple topographic tool to measure the inclination of a surface to predict ballistic paths. It is made up of a rigid frame in the shape of the letter A, at the top of which a plumb line is hung over a crosspiece with a graduated scale. The pendulum wire indicates on the scale the horizontality or the inclination of the surface.
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Clepsydras
The clepsydras is an ancient clock consisting of two superimposed containers, connected by a very small opening and containing water or sand. The passage of time was measured by the amount of water or sand flowing from the upper to the lower vessel. As the volume of water or sand decreased, the pressure also decreased and this prevented the regularity of the flow, jeopardizing the accuracy of the measurement. Later models of clepsydras became more refined and provided the continuous filling of the top container to keep the pressure constant.
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Planetarium
This early planetary model of the solar system was constructed to demonstrate the Copernican model of the solar system. At the centre is the sun. The other rings represent the paths of different planets with their satellites known at the time: Mercury, Venus, the Earth with the Moon, Mars with two satellites, the Asteroid belt, Jupiter with three satellites (one is missing), and even Saturn with its rings. The model can be spun by hand or may be operated by a gear system.
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Pendulum
Galileo discovered that the movement of the pendulum is periodic (i.e, repeats regularly over time even though air friction progressively dampens the oscillations). The regularity of the pendulum, known as isochronism, was noted by Galileo while observing a candelabra in the Cathedral of Pisa. Galileo realized, making a comparison with his heartbeats, that the oscillations of the candelabra (a gigantic pendulum) had the same time duration even when they diminished in amplitude (i.e, widths of swing).
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Variable inclined plank
A wooden plank is hinged to a horizontal board. The upper end of the plank is pegged on two supporting arms in the form of an arc. The inclination of the plank can be changed by pegging it along the arc with a metal peg. A string connects a counterweight through a pulley to a cylinder that rolls down the inclined plank. By changing the plank’s angle one can examine the changes in the motion of the cylinder due to the action of three forces: gravitational force on the counterweight, the frictional force between the plank and cylinder and the pull of the weight of the cylinder.
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The cycloid track
This unusual inclined plane was used by Jacques Bernoulli (1654-1705) to demonstrate Galileo’s idea that the shortest path of a falling body (starting from an orbital position) due to gravity is not a straight line but a curve called a cycloid.
This is significant because it means that the time it takes for an object to fall through a cycloid curve is shorter than in a straight path fall.
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Balistic
Galileo realised that the trajectory of a bullet can be explained by the sum of the two components of its velocity (see diagram). The horizontal component is the one with nearly constant velocity (i.e, nearly constant because air friction would slow it down after a while). The vertical component of its velocity is the one increasing at a constant rate (accelerating at fixed value 9.8m/s2) downwards because of gravity. As a result, the trajectory is a parabola.
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Telescope
Hydrostatic balance
Archipendulum
Clepsydras
Planetarium
Pendulum
Variable inclined plank
The cycloid track
Balistic
ARTISANS OF FLORENCE (AUSTRALIA)
Luigi Rizzo
Director and CEO
Tom Rizzo
Travelling Exhibitions Manager