Please show work for this problem (: To practice Problem-Solving Strategy 8.1 St
ID: 1369003 • Letter: P
Question
Please show work for this problem (:
To practice Problem-Solving Strategy 8.1 Static equilibrium problems. When you lift an object by moving only your forearm, the main lifting muscle in your arm is the biceps. Suppose the mass of a forearm is 1.30 kg . If the biceps is connected to the forearm a distance = 3.00 cm from the elbow, how much force must the biceps exert to hold a 950 g ball at the end of the forearm at distance d = 36.0 cm from the elbow, with the forearm parallel to the floor? How much force must the elbow exert? What is the magnitude of the force exerted by the biceps ? What is the magnitude of the force exerted by the elbow ? Express your answers in newtons separated by a comma. Evaluate whether the answer you obtained for the force exerted by the biceps is reasonable. This question will be shown after you complete previous question(s).Explanation / Answer
Sum the moments about the elbow:
0.960 kg * 9.8m/s² *0.36 m + 1.3kg * 9.8m/s² * 0.36m/2 = Fbiceps * 0.03 m
Fbiceps = 189 N
(Given no other information, "the horizontal distance d of forearm between the elbow and the point where the weight of the forearm acts" is d = L/2 = 36cm / 2 = 18 cm.)
ii) Sum the vertical forces:
(0.960 kg + 1.30)kg * 9.8m/s² + Felbow = Fbiceps
24.5N + Felbow = 189 N
Felbow = 167 N (down)