- #1
way2whack
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Gymnast pictured below performing an Iron Cross has a mass of 65.00 kg. Assume that the forces
in the cables are symmetric and that he is in static equilibrium.
A. Draw a complete free body diagram of the gymnast (just him – he is the system).
B. Calculate the vertical and horizontal components of the cable force acting on his left hand.
**answer: vertical component = 318.83 N horizontal component = -56.13 N**
C. Calculate the moment generated around his left shoulder by the forces in the cable. Make sure you include both components of the cable force.
**answer: -68.60 Nm**
D. Is this moment resisted by the shoulder abductors or adductors? Explain your choice using the results from part C. **answer: This moment is resisted by the shoulder adductors because shoulder abductors are responsible for moving muscles on the arms out to the side, which is a positive moment based on my assignment of rotation. However, my answer was a negative moment about the shoulder joint means the muscles responsible were moving the arms in (clockwise on the left arm).**
E. Would it be harder or easier to hold this move if the cable was vertical instead of tilted inwards? Explain your answer. **I have no idea**
F. If the shoulder muscles have an average moment arm around the shoulder joint of 40 mm, what is the total force required by those muscles to maintain this position? **I have no idea**
http://i.imgur.com/VNdfQ.png <-- picture of gymnast
in the cables are symmetric and that he is in static equilibrium.
A. Draw a complete free body diagram of the gymnast (just him – he is the system).
B. Calculate the vertical and horizontal components of the cable force acting on his left hand.
**answer: vertical component = 318.83 N horizontal component = -56.13 N**
C. Calculate the moment generated around his left shoulder by the forces in the cable. Make sure you include both components of the cable force.
**answer: -68.60 Nm**
D. Is this moment resisted by the shoulder abductors or adductors? Explain your choice using the results from part C. **answer: This moment is resisted by the shoulder adductors because shoulder abductors are responsible for moving muscles on the arms out to the side, which is a positive moment based on my assignment of rotation. However, my answer was a negative moment about the shoulder joint means the muscles responsible were moving the arms in (clockwise on the left arm).**
E. Would it be harder or easier to hold this move if the cable was vertical instead of tilted inwards? Explain your answer. **I have no idea**
F. If the shoulder muscles have an average moment arm around the shoulder joint of 40 mm, what is the total force required by those muscles to maintain this position? **I have no idea**
http://i.imgur.com/VNdfQ.png <-- picture of gymnast