What is the net moment about the elbow caused by all forces in the diagram? The biceps has a moment arm of 6.38 cm with the elbow fulcrum point, and pulls with 576 N of force?at a 75.1 degree angle with the forearm, creating a stabilizing joint reaction force. The?dumbell?has a mass of 17.3 kg and moment arm of 42.9 cm with the elbow. The individual has a body mass of 60 kg and forearm length of 35 cm.