Untitled Document

Physics Demo Number: 099

Approximate

Run Time: 10 min

Bernoulli Effect Aiding in Levitation of a

Rapidly Spinning: Racquetball and/or Ping Pong Ball and/or Golf Ball

Demo Description

The exhaust air from a Shop Vac is used to support a racquetball or a golf ball.

Once the ball is allowed to spin rapidly in the vertically flowing air , then the air stream may be tilted to the side. without the ball falling vertically or being blown horizontally away.

Scientific Principles

Bernoulli Effect
Streamline Air Flow

Equipment

Shop Vac
Racquetball and/or Golf Ball
Fitted Streamline Air Attachment on Vacuum Hose
Hair Dryer Mounted in a Dedicated Wooden Box for use with a Ping Pong Ball

Equipment Location

Alternate quieter (Hair-dryer in dedicated wood box) Setup for Ping Pong Ball is on [F-3-6]
Shop Vac and Ping Pong ball and hose with special end plug are also on [F-3-6].

Instructions

The top photos show the Shop Vac providing real levitation for a golf ball (sometimes replaced by a racquetball) by an intense stream of air from the custom made fitting on the end of the Shop Vac's exhaust hose. (The camera was fast enough to stop the rapid rotation of the ball in this frame.)

Of course the upward blast of air is responsible for the levitation, but the stability is provided by the rapid spinning of the ball and the corresponding lowering of the pressure near the ball on the stand side of the air stream in the photo thanks to the Bernoulli effect.

The bottom photo shows the quieter dedicated hair-dryer in a box in use with a ping pong ball.

Either of these demos require some practice on the part of the lecturer.