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Rocket Car

Single seat CO2 powered rocket cars.

rocket car
Photo by Rose Lincoln

Coriolis Force

What it shows:

The Coriolis force is a pseudo force existing in a frame that rotates with constant angular velocity to a reference frame. It acts on a body moving in the rotating frame to deflect its motion sideways. Here the audience sits in the reference frame, while two volunteers on a rotating platform experience the coriolis force by trying to basket a volleyball.

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Chladni Plates

Accumulation of sand at nodes of vibrating plate reveals resonance patterns.

What It Shows

A Chladni plate consists of a flat sheet of metal, usually circular or square, mounted on a central stalk to a sturdy base. When the plate is oscillating in a particular mode of vibration, the nodes and antinodes that are set up form complex but symmetrical patterns over its surface. The positions of these nodes and antinodes can be seen by sprinkling sand upon the plates; the sand will vibrate away from the antinodes and gather at the nodes.

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Conservation of Charge to 3 Sig Figs

What it shows:

Electricity is never created or destroyed, but only transferred. Rubbing fur and Teflon™ together transfers charge (electrons) from the fur to the Teflon, making the Teflon negatively charged. Conservation of charge requires the fur to become equally and oppositely charged as is demonstrated in this experiment to an accuracy of ≤1%.

How it works:

The difficulty in demonstrating charge conservation quantitatively lies in catching all the charge before it leaks away, the fur being the main problem. This is overcome...

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Hand Cranked AC Generator

Observe the induced current in a gimbaled coil as it rotates in Earth's magnetic field.

What it Shows

A changing magnetic flux through a circular coil of wire induces a current in the wire. By spinning a circular coil of wire at constant frequency and measuring the induced voltage across its ends we can find the local direction and magnitude of the Earth's magnetic field as it passes through the coil. The commutators of the coil are configured to produce an alternating current.

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Radiometer

Detection of IR radiation from hair dryer and/or special IR source.

What it Shows:

Detection of infra-red radiation by the rotation of a paddle-wheel vane inside a low pressure flask.

How it Works:

A radiometer consists of a partially evacuated flask containing a four bladed vane (see figure 1). One side of each blade is a matt black, the other silver. The black surface, being a better absorber and radiator of heat, warms the air above its surface more than the silver. The resulting higher kinetic energy of these air...

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Edge Diffraction

What it shows:

A point light source will produce seemingly sharp shadows which turn out to be not at all sharp when viewed under magnification. Narrow interference bands are seen within the shadow of a straight edge while more complicated shapes yield more complicated interference bands and striations.

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CRT Paddle Wheel

A beam of cathode rays (electrons) impinging on a paddle wheel cause it to spin and travel down the vacuum tube.

crookes tubes

What it Shows

A paddle wheel is suspended by its axle inside a Crookes tube so that when the paddle vanes spin the entire wheel is free to travel the length of the tube...

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Mixing and Unmixing

Food coloring in glycerine is mixed by turning a drum, then unmixed by reversing. Has entropy decreased?

What it shows:

Ink is squirted into a fluid and mixed in until it disappears. By precisely undoing the motions in the reverse direction, the ink becomes unmixed! The demonstration seems to defy thermodynamics in that it appears that entropy decreases, but in actuality the reversible mixing is made possible by insuring that the mixing/unmixing is done without turbulence.

How it works:

The space between two, transparent and concentric...

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Hot and Cold Gas in Balloons

A balloon is dropped in boiling water, and another balloon is cooled with liquid nitrogen to demonstrate the effect of temperature on volume of gas in a balloon.

A 4 liter beaker on a hot plate, with a liter of water boiling within. A prepared balloon, filled with air and tied so that it just fits in the beaker, is dropped into the beaker. The balloon expands to seal the beaker and is forced up by the vapor pressure, ending up on top of the beaker, too large to fit inside.

A foam ice bucket will hold a helium ballon that is large enough to seal around the inside of the bucket...

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