Table of Mechanics Demonstration List of Mechanics Equipment & Supplies Lecture Demonstrations

# Shear Cards, 1R30.10

Topic and Concept:

Location:

Abstract:

Use a tall stack of cards placed sequentially off-center to create a ledge.

 Equipment Location ID Number Stack of Cards ME, Bay , Shelf #

Important Setup Notes:

• This demonstration may require practice.

Setup and Procedure:

1. Place a squarely stacked deck of cards on the lecture bench.
2. Starting from the bottom, carefully nudge each card out about a few millimeters in a sequential fashion.

Cautions, Warnings, or Safety Concerns:

• N/A

Discussion:

In the simpler case of two stacked cards, there is a sum of torques acting on the top card. On each element of mass in the card, the is a downward force due to gravity. There is a fulcrum created when the top card is slid off center off the bottom card. The top card will remain horizontal if the torque pushing the card onto the bottom card is greater than that pushing the cantilevered portion downward. This analysis can be applied to a several cards stacked in this fashion.

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