NYU Physics Demos

Central Forces

Topics: Mechanics - Centrifugal Force, Centripetal Force

Equipment: Central Force Apparatus

Setup: Plug in.

Once plugged in, the motor begins to spin two perpendicular rings around a central axis. These rings are made of metal and tend to pull themselves back to a circular shape by their own tension. When they spin rapidly, centrifugal forces pull them apart into a noticeably ovular shape. The rings become wider along the x-axis and shorter along the y-axis.

Location: Shelf B-h5

Notes: There are several apparatuses that demonstrate a similar phenomenon. Pictures and brief descriptions of these demos are included on the next page. These demos are shelved separately from the motor. Search the demo page “Motors” to locate the motor shelf.

CAUTION: The motor is strong and spins very quickly- DO NOT place your hand near the rotating object.

Keywords: Force, Centrifuge, Tension, Rotate, Bend, Pull

In the following demo, two balls are attached to two thin metal strips. When they start to spin, the force on the balls is strong enough to bend the metal outward.

In the following demo, four balls are free to slide through curved metal rods. These rods will not compress like the demo on the previous page. Instead, when it starts to spin, the balls move upwards and outwards while the rods maintain their shape.

In the following demo, two masses can move freely along a horizontal rod. These masses start at the center, and when they start to spin they will move to the ends of the rod.

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