Question

How much force (in N) must the biceps muscle exert when a 25.0 kg mass is held in the hand in a stationary position when the arm is 17.4° below the horizontal? Assume the mass of the forearm is 2.46 kg. Distances relative to the elbow joint are reb = 5.12 cm; recg = 16.5 cm; ren = 37.5 cm where the distances are: eb = elbow—biceps; ecg = elbow—forearm center of gravity; eh = elbow-hand.

Answer 1

B 2.462 AD = 8eb = 5:12 am AC = Vecg = 16.5cm . A " 717.40 ċ- AB = Yen = 37.5 cm Taking equilibrium of 259 rotation about elbow joint FX AD COB 17.4°= 2.469 x AC 60317.4° +259 x AB Cos 17.4° » FXXebCostoy = (2.46 X Vecg +25 X 8en) g costs.yo F = (2.46 Xecg + 25 x 8en) g = 191.03 N. F ' / 2.46x165 +25 x 37.5) N t 5.12 5.12

vadius of columm r= 0.890 m = 0.445 original length L = 6.63 m m= 2789 kg Yinarele = 500 x 10°N/m? using Ymortle = f ho ng L AL= EL A moble 18 marble 9789x9.86.63 So X10° x 3.14 X (0-44 ) LOL = 5.83 x 10m