*4-4. Determine the moment about point A of each of the 4 three forces acting on the beam. 4-5. Determine the moment about point B of each of the three forces acting on the beam. F₁ = 375 lb F2 = 500 lb A 4 3 B 0.5 ft 8 ft- 6 ft- -5 ft- 30° F3 = 160 lb 4-21. In order to pull out the nail at B, the force F exerted on the handle of the hammer must produce a clockwise moment of 500 lb in. about point A. Determine the required magnitude of force F. 30° 18 in. 5 in. B 4.4 PRINCIPLE OF MOMENTS 4-15. Two men exert forces of F = 139 80 lb and P: = 50 lb on the ropes. Determine the moment of each force about A. Which way will the pole rotate, clockwise or counterclockwise? *4-16. If the man at B exerts a force of P = 30 lb on his 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. B 45° 12 ft A Probs. 4-15/16 6 ft 4 3