If the maximum force exerted by the athlete is 360 N and the

If the maximum force exerted by the athlete is 360 N and the angle between OF (perpendicular to the javelin) and x axis is 45 degree, determine the moment about the shoulder joint O. Use the dimensions of your own arm and forearm. The forearm is parallel to line OF Which muscle is generating that force causes rotation about the shoulder joint? Can you estimate the force in that muscle? State your assumptions. Explain your observations in the following x-ray. Be as through as possible about the location and type of phenomenon you are observing Which leg does this image represent? Why? Use medical terms.

Solution

Muscles of rotator cuff use to rotate the shoulder around the joint. That includes four muscles Supraspinatus, Dletoid, Infraspinatus and Teres minor.

F = mg sin

M = mass of javelin+ mass of arm which takes as 800g + 3.6Kg, = 4.4Kg

Gravity g = 9.8m/s2 , = 45⁰ for optimal flight angle

F = 4.4 x 9.8 x sin45⁰ = 43.12 x 0.85 = 36.66 Newton

The x-ray image is representing right leg. That is lateral view and showing tibia front of fibula.