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Jupiter's Satellites

Static model of satellite orbits.

What it shows:

Static 3-D model showing the orbital paths of Jupiter's satellites.

How it works:

The model marks the orbital paths of the Jovian satellites to a scale of 1.5cm = 106 km. This scale allows the orbit of the outermost satellite Sinope to fit within a 1m × 1m plywood base. The orbits of the outer 8 satellites are marked using loops of 2mm × 1mm spring steel supported to their correct heights by 5mm Plexiglas rods (Pasiphae rising to the greatest height of 42cm). The...

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Stack of Blocks

A dozen blocks are stacked on top of each other over the edge of the table seemingly defying gravity.

What it shows:

N objects of unit length can be stacked on top of each other so that the top object sticks out over the edge of the lecture bench by a distance equal to 1

1/2 + 1/4 + 1/6 + 1/8 + ... + 1/(2N)

For N approaching ∞, the diverging infinite sum suggests that the top of the pile can stick out an infinite distance. In actuality the divergence is slow, 2 and our more practical stack of a dozen 2 × 4 "blocks" can...

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Falling Faster than 'g'

What it shows:

Allow a board to rotate under the force of gravity and the free end will accelerate at a rate greater than g. Relation between angular acceleration and linear acceleration seems to give free-fall paradox.

How it works:

If a board, held in a vertical position with one end resting on the table, is allowed to...

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Shive Wave Machine

Rods attached to metal spine; transverse wave generator shows the reflection of waves free, fixed, terminated and transition boundaries.

What it shows

Mechanical demonstration of transverse standing or traveling waves using the Shive wave machine.

How it works

The Shive wave machine consists of a series of horizontal metal rods 1.25 cm apart coupled by a torsion wire. A pulse can be sent down the machine by displacing the end rods (when doing this by hand, pull down on more than one rod as the connections are delicate and do break). The far...

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Semimusical Blocks of Wood

What it shows:

Drop a piece of wood on the floor and listen to the sound it makes. It may sound like noise, but it also makes a "semimusical" sound which is so poor in quality that one would be hard pressed to call it musical. Yet it is not pure noise because the sound contains a series of regular impulses that have a pitch. This may be demonstrated by dropping wood bars (one by one) onto the floor — a musical scale or tune is easily recognized.

How it works:

The tuned wood (oak) bars are 6½" long and 1" wide with thicknesses...

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Bird on a High-Voltage Transmission Line

What it shows:

Why doesn't a bird sitting on a high-voltage wire get electrocuted? This demonstration addresses that question and serves as a model of the situation.

How it works:

The important concept conveyed is that there needs to be a voltage difference across a conducting medium for current to flow through the medium. In this situation the conducting medium is a bird sitting on a high-voltage wire. The voltage on the wire is the voltage of the whole length of wire with respect to the ground. Although the bird on the...

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