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The following simulation models the motion of a ball falling in air that exerts a frictional force on the ball that is in the opposite direction
as the ball's velocity and has a magnitude proportional to the square of the ball's speed. The proportionality constant is k.
Notice that a ball dropped from rest eventually reaches a constant speed
called the terminal speed. This is equal to mg/k where g is the acceleration
due to gravity and k is a constant that is proportional to the force of
air resistance at a certain speed. You can set a value of k before
clicking on a link in order to observe its effect on the motion of the
Answer the following questions:
1. Suppose a skydiver is falling at her terminal speed when she
pulls her 'chute. During the time interval that the chute opens,
what direction is her acceleration?
2. If a projectile is projected downward with an initial speed
greater than sqrt(mg/k), the object's terminal speed, is its instantaneous acceleration,
at any instant before it reaches terminal speed, positive or negative?
| Position vs. Time
Velocity vs. Time
Acceleration vs. Time
are scriptable Java Applets written by Wolfgang Christian of Davison College.