Moment of Inertia: alterations that occur with manipulations of the upper and lower extremities

Part I 

Question 1 

In classical physics, any object resist change in motion despite the change in direction. This is what Newton describes in his first law of motion that a body keeps moving in a straight line and at a constant speed unless it is acted upon by an external force. Therefore, by stretching the arm straight, the angular speed remains the same. When the arms are brought near the chest, the angular speed is still constant. This is because there is no external force that acts on the body apart from air resistance. 

Question 2 

In the second case, the air resistance is reduced since the surface acted upon by air resistance is small. Consequently, the angular velocity will increase when the legs are brought in, and the arms are brought in. 

Question 3 

When the knees are flexed, and the arms kept closed the angular speed will increase by a small value since the radius of rotation reduces. A reduction in the radius of rotation always increases the value of omega, which in turn increases the angular speed. When the arm and legs have stretched the radius of rotation increases, therefore, reducing the value of omega the air resistance will also increase; hence the angular speed will decrease. 

Question 4 

When the arms are kept closed, and the legs have closed the surface of rotation increases, which raises the value of omega thus reducing the angular speed. 

Part II 

It is observed that an increase in metabolic surface leads to a parallel increase in mechanical power and the electromyography. Consequently, this leads to an increase in limb mass or the limb moment of inertia. The result is that there is an influence on the transverse axis influencing the angular speed depending on which limbs are manipulated.