The deltoid muscle is the main muscle that allows you to raise your arm or even

Question

The deltoid muscle is the main muscle that allows you to raise your arm or even hold it out. It is connected to the humerus of the upper arm. (See part (a) of the figure .) The person shown is holding his arm out horizontally with a 2.76 kg weight in his hand. This weight is 60.0 cm from the shoulder joint. His forearm (including his hand) has a mass of 2.42 kg and is 34.0 cm long; its center of mass is 43.0 cm from the shoulder joint, measured along the arm. His upper arm is 26.0 cm long and has a mass of 2.55 kg; its center of mass is 13.0 cm from the shoulder joint. The deltoid muscle is attached to the humerus 15.0 cm from the shoulder joint and makes a 14.0 degrees angle with the humerus. (See part (b) of the figure.) What is the tension in the deltoid muscle? If the person was using wrist wieghts instead of one in his hand, what would be the tension in the deltoid muscle then? Let the new position of the weights be 49.4 cm from the shoulder joint.

Explanation / Answer

Torque t = F * distance to pivot point        W = M_1 = 2.76 kg * 9.8 * 0.6 m            Forearm   M_2 = 2.42* 9.8 * 0.43 m            Upeer arm M_3 = 2.55kg * 9.8* 0.13 m        M_4   = F * 0.15 sin ( 14 degrees ) tension in the deltoid muscle   is               At equilibrium M_4   = M_1 + M_2 + M_3 = F            substitute the values solve for F to get solution             

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.