This varies from person to person. There is a point in time at which hormones in a persons body begin to loose their effective functions, a period I have heard reffered to as adult puberty. In women this is marked by menopause. While you can still theoretically maintain a healthy body at this time, it becomes increasingly difficult. Maintaining a healthy diet and constant exercise are essential to achieving this. A doctor won't tell you much more than this.
According to the relationship between force and acceleration, described in Newton's 2nd law of motion, increasing the force of the object would also increase the objects acceleration in the same direction to which the force is applied. It essentially starts to move even faster, than it had been before. Since the object is accelerating it changing its speed at an even faster rate.
Crying over a math test
SO FUNNNN
