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

# Rope and Three Students, 1J30.25a

Topic and Concept:

Location:

Abstract:

Two large, strong students pull in opposite directions on the ends of a rope. A small student then pushes/pulls on the middle of the rope in a direction perpendicular to the rope.

 Equipment Location ID Number Rope ME, Bay B7, Shelf #1

Important Setup Notes:

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Setup and Procedure:

1. Have two large, strong students pull in opposing directions on an end of the rope (as pictured) to produce a static system.
2. Have the third, smaller student push or pull on the middle of the rope in a direction perpendicular to it.

Cautions, Warnings, or Safety Concerns:

• Make sure the small student does the pushing/pulling slowly so as to give the other two students time to react and catch themselves.

Discussion:

After the two bigger students pull the rope taught, it is in static equilibrium. It doesn't take much force to push or pull the rope in the direction perpendicular to the rope giving it a net acceleration. This puts a net torque on each of the bigger students which causes them to fall inward toward the middle. This is how a relatively smaller, weaker person can cause to big, stronger people to loose the match.

Videos:

References:

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