Mechanical Engineering Tutorial 4 Moment of a force Harem Gh. Hussein 22- Jan-2015

Statics’ Subtopics Units system, force system, parallelogram law Forces components, resultant of coplanar forces Components of forces in space, moment of a force, moment of couples Equilibrium, free body diagram, friction Centroids and Centers of gravity, centroids of area Moment of Inertia Second moment of area by integration radius of gyration Prepared by Harem G. H.

Problem 1 The handle of the hammer is subjected to the force of F=20 lb Determine the moment of this force about the point A. Prepared by Harem G. H.

Solution 1 Prepared by Harem G. H.

Problem 2 Determine the angle θ (0o≤ θ ≤180o) of the force F so that it produces a maximum moment and a minimum moment about point A. Also, what are the magnitudes of these maximum and minimum moments? Prepared by Harem G. H.

Solution 2 Maximum Moment Minimum Moment Prepared by Harem G. H.

Solution 2 Prepared by Harem G. H.

Solution 2 Prepared by Harem G. H.

Problem 3 In order to raise the lamp post from the position shown, the force F on the cable must create a counterclockwise moment of 1500 lb.ft about point A. Determine the magnitude of F that must be applied to the cable. Prepared by Harem G. H.

Solution 3 Prepared by Harem G. H.

Solution 3 Prepared by Harem G. H.

Problem 4 In order to hold the wheelbarrow in the position shown, force F must produce a counterclockwise moment of 200 N.m about the axle at A. Determine the required magnitude of force F. Prepared by Harem G. H.

Solution 4 Prepared by Harem G. H.

Problem 5 Determine the required magnitude of force F if the resultant couple moment on the frame is200 lb.ft clockwise. Prepared by Harem G. H.

Solution 5 Prepared by Harem G. H.

Problem 6 Determine the resultant couple moment acting on the beam. Solve the problem two ways: (a) sum moments about point O; and (b) sum moments about point A. Prepared by Harem G. H.

Solution 6 Prepared by Harem G. H.

Problem 7 Determine the required magnitude of force F, if the resultant couple moment on the beam is to be zero. Prepared by Harem G. H.

Solution 7 Prepared by Harem G. H.

Solution 7 Prepared by Harem G. H.

Problem 8 Two couples act on the frame. If d=4 , determine the resultant couple moment. Compute the result by resolving each force into x and y components and (a) finding the moment of each couple and (b) summing the moments of all the force components about point A. Prepared by Harem G. H.

Solution 8 Prepared by Harem G. H.

Any Question? Thank you! Prepared by Harem G. H.