Physics Demo Number: 143

Approximate

Run Time: 5 min

Board Leaned Against Wall for Modeling Extension-Ladder Statics

Demo Description

A long board is used to lean against a wall and have its base rest on the floor.

One may devise friction and placement conditions that will lead to stable repose of the ladder or not.

Scientific Principles

• Static conditions for extension-ladder stability while leaned against a wall.

Equipment

• A metal shelf.

• A wood board.

Equipment Location

• A metal shelf hangs on wall at the end of [E]-[F] aisle.

• A backup metal shelf is on top of the [E-4] column .

• The wood board leans against wall at the end of [E]-[F] aisle.

Instructions

The first photo shows the board leaning against a wall in the storeroom. The second photo shows the board after swapping its “up” and “down” ends .

Note that the two white dots in the top of first photo, as well as the three white dots on the top end in photo two are all PVC furniture slides attached to the board to give low friction contacts with the floor or wall.

The last photo, borrowed from (081) ,shows the metal shelf which may be used to give a slicker floor than the cork one in lecture hall.

Writeup created by David A. Burba

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