Module 4.1: FallFriction

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The FallFriction model builds on the Fall model by adding air friction. As you will notice, the stocks and flows for the FallFriction and Fall models are the same, but the FallFriction model adds a few more terms. Let's take a look at some of the new terms.

Mass: The object's mass can be adjusted using the Total Mass slider. Mass impacts the object's weight and acceleration.
Weight: The object's weight is its mass times its acceleration due to gravity. Acceleration due to gravity is as always, -9.81 m/s2. Mass is controlled by the Total Mass slider. We need to have weight in the model because it impacts the total force.
Total Force: Total force adds the object's weight and the air friction, then is divided by mass to calculate the object's acceleration.
Air friction is a slightly more complicated term, so we'll start by looking at its term components.
Radius: Radius is controlled by the Object Radius slider.
Projected area: This term is calculated by squaring the radius and multiplying it by π (it's a ball, remember?).
Air friction: Air friction is calculated using the value for Newtonian friction, F = -0.65, multiplied by the projected area, velocity, and the absolute value of velocity.
The graph and table show values for position and speed over time.