# Discussion+session5 (1).pptx - ENGR 30 STATICS Discussion...

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Chapter 7 / Exercise 3
Engineering Fundamentals: An Introduction to Engineering
Moaveni
Expert Verified
ENGR 30 STATICS Discussion Session 5&6 Winter 2018 1
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Chapter 7 / Exercise 3
Engineering Fundamentals: An Introduction to Engineering
Moaveni
Expert Verified
Two-force member Requiring that the sum of forces and total moment in any direction be zero leads to the conclusion that F 1 and F 2 must have equal magnitude but opposite sense, and on the same line. Three-force member Since the rigid body is in equilibrium, the sum of the moments of F 1 , F 2 , and F 3 about any axis must be zero. It follows that the moment of F 3 about D must be zero as well and that the line of action of F 3 must pass through D . The lines of action of the three forces must be concurrent or parallel. 7 Fundamental Concepts
Sample Problem A slender rod of length L is attached to collars that can slide freely along the guides shown. Knowing that the rod is in equilibrium, derive an expression for the angle θ in terms of the angle β. W A G B θ β β A B O W A B tan L cos 2 L sin 2 tan GB L sin 2 GO L cos Therefore : tan GO Where : 1 1 1 Fromthe force geometry : GB
Sample Problem Two force member, the force at reactions D and C must pass points DC B x B y
Fundamental Concepts Idealized 3D structural supports 5
Fundamental Concepts Idealized 3D structural supports (for some problem, the couple-moment must be assumed zero to provide statical determinacy, if there are no active forces on that directions) 6
Fundamental Concepts Idealized 3D structural supports 7