The deltoid muscle is the main muscle that allows you to raise your arm or even
ID: 1265025 • Letter: T
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 (Figure 1) .) The person shown is holding his arm out horizontally with a 2.79kg weight in his hand. This weight is 59.3cm from the shoulder joint. His forearm (including his hand) has a mass of 2.38kg and is 34.2cm long; its center of mass is 42.4cm from the shoulder joint, measured along the arm. His upper arm is 28cm long and has a mass of 2.73kg ; its center of mass is 11cm from the shoulder joint. The deltoid muscle is attached to the humerus 15.1cm from the shoulder joint and makes a 14? angle with the humerus. (See part (b) of the figure.)
A) What is the tension in the deltoid muscle? T= ___ N
B) 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 49.5cm from the shoulder joint. T =___N
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 (Figure 1) .) The person shown is holding his arm out horizontally with a 2.79kg weight in his hand. This weight is 59.3cm from the shoulder joint. His forearm (including his hand) has a mass of 2.38kg and is 34.2cm long; its center of mass is 42.4cm from the shoulder joint, measured along the arm. His upper arm is 28cm long and has a mass of 2.73kg ; its center of mass is 11cm from the shoulder joint. The deltoid muscle is attached to the humerus 15.1cm from the shoulder joint and makes a 14? angle with the humerus. (See part (b) of the figure.) A) What is the tension in the deltoid muscle? T= ___ N B) 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 49.5cm from the shoulder joint. T =___NExplanation / Answer
apply the law of conservation of moments as
sum of M = 0
T d sin theta - ( sum of Ms) *g
T sin 14 * 0.151 -((2.79 * 0.593) +(2.38* 0.0.424) + (2.73 * 0.11))* 9.8
T * 0.0365 = 20.14
T = 20.14/0.0365
T = 552 N
--------------------------------
as Arm segments come into play now
Sum of M = 0
T sin 14 * 0.151 -((2.79 *(0.342 + 0.28)) + (2.44 * 0.424) + (2.73*0.11))*9.8
T * 0.0365 = 30.088
T = 30.088/0.0365
T = 824.338 N
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