As objects fall, they increase their speed due to the downward pull of gravity. Air resistance counteracts gravity's pull by resisting the downward motion of the object. The amount of air resistance depends upon a variety of factors, most noticeably, the object's shape and speed. As objects move faster, they encounter more air resistance. When the amount of upward air resistance force is equal to the downward gravity force, the object encounters a balance of forces and is said to have reached a terminal velocity.

1. Determine the terminal velocity of a coffee filter using a motion sensor.
2. Increase the mass of the falling object by stacking several coffee filters on top of one another. This will increase the terminal velocity.

Mass of a coffee filter = 0.9 g