There is no air resistance acting in the upwards direction, and there is a resultant force acting downwards so the skydiver accelerates towards the ground. As the skydiver gains speed, their ...
proportional to the resultant force on the object inversely proportional to the mass of the object In other words, the acceleration of an object increases if the resultant force on it increases ...
The integrals are weighted by integer powers the thickness coordinate z (or x 3). Stress resultants are so defined to represent the effect of stress as a membrane force N (zero power in z), bending ...