Lecture 42: Course Material Review

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Lecture 42: Course Material Review
ENGI 1313 Mechanics I Lecture 42: Course Material Review

Example 42-01 If the resultant couple moment of the three couples acting on the triangular block is to be zero, determine the magnitudes of forces F and P.

Example (cont.) Technical Concept Couple Moment

Example (cont.) Analysis d d d

Example 42-02 The telephone pole of negligible thickness is subjected to the force of 80 lb directed as shown. It is supported by the cable BCD and can be assumed pinned at its base A. In order to provide clearance for a sidewalk right of way, where D is located, the strut CE is attached at C, as shown by the dashed lines (cable segment CD is removed). If the tension in CD′ is to be twice the tension in BCD, determine the height h for placement of the strut CE.

Example 42-02 (cont.) Technical Approach 2D Equilibrium FBD
Complete FBD? Yes for initial condition Find TBD TBD Ax Ay

Example (cont.) Find TBD TBD Ax Ay

Example (cont.) Find TCD’ Find LCE Find h TBD TCD’ Ax Ay

Example 42-03 The pipe is hoisted using the tongs. If the coefficient of static friction at A and B is μs, determine the smallest dimension b so that any pipe of inner diameter d can be lifted.

Example (cont.) W Global FBD FBD of Tong 0.5W FB FB Cx NB Cy FB

Example (cont.) W For Lifting 0.5W FB FB Cx NB Cy FB

References Hibbeler (2007)