NEE 1106 Engineering Mechanics PDF

NEE 1106 Engineering Mechanics: Statics of Rigid Bodies Moment of a Force about a Point Moment of a Force about an axis – the tendency of a force to rotate a body about an axis. Let F be a force and O a point that is not on the line of action of F, as shown in the figure below. Note that t...

NEE 1106 Engineering Mechanics: Statics of Rigid Bodies Moment of a Force about a Point Moment of a Force about an axis – the tendency of a force to rotate a body about an axis. Let F be a force and O a point that is not on the line of action of F, as shown in the figure below. Note that the force F and the point O determine a unique plane. We let A be any point on the line of action of F and define d to be the vector from point O to point A. The moment of the force F about point O, Mo = F x d called the moment center, is defined as where : Mo – moment of a force (N-m) F – force in N d – moment arm of force in meter Varignon’s Theorem: “ The moment of a force about a point is equal to the sum of the moments of its components about that point. (M R )o = Fd; (M R)o = F1 d 1 - F2 d 2 + F3 d 3 Problem: For each case illustrated in the figure below, determine the moment of the force about point O. (1) (2) Problem: For each case illustrated in the figure below, determine the moment of the force about point O. (3) (4) 5. Problem: Determine the resultant moment of the four forces acting on the rod shown in the figure below at point O. 6. Problem: Determine the resultant moment of the four forces acting on the rod shown in the figure below at point O. 6. Solution: 7. Problem: Determine the moment about point B of each of the three forces acting on the beam. 7. Solution: 8. Problem: If the man at B exerts a force P = 30 lb on this rope, determine the magnitude of the force F the man at C must exert to prevent the pole from rotating i.e., so the resultant moment about A of both forces is zero. 8. Solution:  9. Problem: Determine the resultant of the given force and its loca rom A. 9. Solution:  10. Problem: Determine the resultant of the given loads and its loc from A.  9. Problem: Determine the resultant of the given force and its loca rom A.