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WFU Physics Lecture Demonstrations

Precession with Gyroscopes

PIRA 1Q50.50

Image:

Photo of Demo

Description:

"Gravity produces a torque perpendicular to both the axis of the gyroscope and the vertical, and thus causes the horizontal precession. On a less abstract level, the precession can be explained in terms of the downward pull of gravity that tries to make the wheel rotate faster at the bottom than at the top. Since the wheel is rigid, this can happen only if the wheel moves horizontally in the direction in which the bottom of the wheel is spinning. The earth is a large gyroscope that precesses once every 26,000 years due to the gravitational torque exerted by the sun on the slight bulge at the equator. Note that the precessional frequency is inversely proportional to the frequency at which the gyroscope is spinning. This fact can be illustrated by observing carefully the precession as the gyroscope slows down. Furthermore, the precession frequency is independent of the angle that the axis makes with the horizontal. The torque is greatest when the axis is horizontal, but so also is the distance it has to move to precess once around, and the effects just cancel."

Recipe and
Location:

Cenco Gyro w/Stand
or
Toy Gyro w/String
Electric Spinner

Video:

Streaming Video:

None

MPG Video:

None

Real Video:

None

Notes:

 

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Demos

Mechanics
Fluid Mechanics
Waves
Thermodynamics
E&M
Optics
Modern
Astronomy
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100 Olin Physical Laboratory
Wake Forest University
Winston-Salem, NC 27109-7507
Phone: (336) 758-5337, FAX: (336) 758-6142
E-mail:
wfuphys@wfu.edu