Please also provide explanation
1. Draw a FBD of a person who is holding a 9 pound weight in her hand. Her shoulder is
abducted to 90o, her forearm is fully extended and her wrist is at neutral. The weight of her upper extremity (UE) is 11.1 pounds. The center of gravity of the 9 pound weight is 22.5 inches from the axis of rotation. The center of gravity of her UEis 8.75 inches distal to the axis of rotation. The deltoid muscle, which is attached 4.8 inches distal to the axis of rotation, is providing the force to maintain the abducted position of the UE.
a. Calculate the torque of gravity. Show all your work. In your drawing, which direction (+ or -) is the torque of gravity acting?
b. Calculate the torque of the deltoid muscle holding the UE/weight in the abducted
position. Which direction is the torque of the muscle acting?
c. Calculate the force of the deltoid muscle. Show all your work.
(a) From the FBD we can understand that how the forces w and W
are acting on the arm .
Now torque due to the weight will be
= w*22.5 + (W*8.75)
= (9*22.5 ) +(11.1*8.75) = 299.625 lbs-inches
Direction will be clockwise therefore +ve .
(b)
Torque due to the deltoid muscles should be same as by gravity and
in the opposite direction to maintain the equilibrium
Therefore
torque due to deltoid muscle = - 299.625 lbs-inches
-ve sign indicate that the direction must be anticlockwise.
(c)
Now we know that the torque due to deltoid muscle
F*4.8 = 299.625
F = 62.42 lbs
Hence the force applied by the deltoid muscles will be 62.42
pounds.
Please also provide explanation 1. Draw a FBD of a person who is holding a 9...
Draw a FBD of a person who is holding a 9 pound weight in her hand. Her shoulder is abducted to 90o, her forearm is fully extended and her wrist is at neutral. The weight of her upper extremity (UE) is 11.1 pounds. The center of gravity of the 9 pound weight is 22.5 inches from the axis of rotation. The center of gravity of her UE is 8.75 inches distal to the axis of rotation. The deltoid muscle, which...
1. Draw a FBD of a person who is holding a 9 pound weight in her hand. Her shoulder is abducted to 90o, her forearm is fully extended and her wrist is at neutral. The weight of her upper extremity (UE) is 11.1 pounds. The center of gravity of the 9 pound weight is 22.5 inches from the axis of rotation. The center of gravity of her UE is 8.75 inches distal to the axis of rotation. The deltoid muscle,...
Draw a FBD of a person who is holding a 9 pound weight in her hand. Her shoulder is abducted to 90o, her forearm is fully extended and her wrist is at neutral. The weight of her upper extremity (UE) is 11.1 pounds. The center of gravity of the 9 pound weight is 22.5 inches from the axis of rotation. The center of gravity of her UE is 8.75 inches distal to the axis of rotation. The deltoid muscle, which...
Draw a FBD of a person who is holding a 9 pound weight in her hand. Her shoulder is abducted to 90o, her forearm is fully extended and her wrist is at neutral. The weight of her upper extremity (UE) is 11.1 pounds. The center of gravity of the 9 pound weight is 22.5 inches from the axis of rotation. The center of gravity of her UE is 8.75 inches distal to the axis of rotation. The deltoid muscle, which...
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