Descent Dynamics Plots
The Descent Velocity Profile below illustrates how initially, aerodynamic drag is negligible and therefore, the acceleration is constant. Then above ten mph, the effect of drag progressively slows the acceleration down until after 40 seconds, the acceleration is near zero as the drag force nearly balances out the downward pull of gravity along the slope. This flattening out of the velocity curve due to drag is what is known as Terminal Velocity.
Once you understand the velocity profile, the position profile makes sense. Initially, the change in position is small per second reflecting initial stage of the descent. As the velocity increases, the distance covered per second increases and moves towards a constant distance per second as the terminal velocity is reached.
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