When you lift an object by moving only your forearm, the main lifting muscle in

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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 1.50 kg . If the biceps is connected to the forearm a distance dbiceps = 2.50 cmfrom the elbow, how much force Fbiceps must the biceps exert to hold a 850 g ball at the end of the forearm at distance dball = 33.0 cm from the elbow, with the forearm parallel to the floor? How much force Felbowmust the elbow exert? (Figure 1)

Although it is uncommon, orthopedic surgeons have seen patients who have torn their biceps tendon when forces of greater than 390 N have been exerted on the tendon with the arm bent at the elbow so that the forearm is parallel to the ground. What is the minimum mass of a ball Mball such a patient might have held to cause the biceps tendon to tear?

Part l PSS 8.1: Static equilibrium problems What is the magnitude of the force exerted by the biceps Fbiceps? What is the magnitude of the force exerted by the elbow Felbow? Learning Goal Express your answers in newtons separated by a comma. To practice Problem-Solving Strategy 8.1 Static equilibrium problems. Fbiceps. Felbow-207, 184 N, N 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 1.50 kg. If the biceps is connected to the forearm a distance dbiceps2.50 cm from the elbow, how much force Fbiceps must the biceps exert to hold a 850 g ball at the end of the forearm at distance dbll33.0 cm from the elbow, with the forearm parallel to the floor? How much force Felbow must the elbow exert? (Figure 1) Submit My Answers Give Up Correct ASSESS Evaluate whether the answer you obtained for the force exerted by the biceps is reasonable Part J of 1 Although it is uncommon, orthopedic surgeons have seen patients who have torn their biceps tendon when forces of greater than 390 N have been exerted on the tendon with the arm bent at the elbow so that the forearm is parallel to the ground. What is the minimum mass of a ball Mball such a patient might have held to cause the biceps tendon to tear? Figure 1 Express your answer in kilograms Biceps ball ball = kg Submit My Answers Give Up biceps Incorrect Try Again; 5 attempts remaining vide Feedback Continue

Explanation / Answer

Torque net = 0

0= (distance biceps * Force biceps)-(.5*mass forearm*gravity*distance ball)-(Mass ball*g*distance ball)

Earlier we got from first question, Force of biceps, which = 207N
Now use 390N instead of 207N.

Just plug in 390N for Force of biceps in the Net Torque equation and plug in all other values in the equation except Mass of ball, which is what we are solving for.

Then obtain the mass of the ball

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