Tiêu đề 04 Forces Tutorial Solutions.pdf ✅

St. Andrew’s Junior College H2 Physics 4-2 Finding moments about a point Calculate the moment due to the specified force about the given pivot. ▪ Length of the boom is 3 m. Calculate the moment of F about hinge .............. N m Clockwise or Anticlockwise? .................... Workings Moment = (120)(0.75 sin 60°) = 77.9 N m, anticlockwise Calculate the moment of T about hinge (there are 2 methods, try both!) .............. N m Clockwise or Anticlockwise? .................... Angle between T and boom = 180° – 120° – 4 = 15° Method 1: Resolve T perpendicular to boom. Moment = (4116 sin 15°)(3) = 3196 N m, anticlockwise Angle between T and horizontal = 45° Method 2: Resolve T into horizontal and vertical component, and find vertical and horizontal displacement to hinge from T. Moment = (4116 cos 45°)(3 sin 60°) - (4116 sin 45°)(3 cos 60°) = 3196 N m, anticlockwise T = 4116 N F = 120 N