Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

12.1 INTRODUCTION

· A force is an important type of mechanical effect, but it doesn't explain bending. For this we use moments.

· The classic example is the see-saw,

· Considering moments, convert the cases given on the left to those requested on the right.

· Consider the case of a vise. The bottom member must resist the moment caused when the jaws are tightened.

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· If we look at a normal step ladder we can see that both halves can be analyzed using moments about the top platform.

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· Certain varieties of tools amplify forces by using moment arms.

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· We will use the terms moment (M) and torque (T). Numerically the two terms are identical, and are calculated the same way. Typically Moment is used when describing a bending, and Torque is used when describing a twisting moment on a shaft.