Gizmo: Free Fall Tower
Vocabulary: acceleration, instantaneous velocity, terminal velocity
Prior Knowledge Questions (Do these BEFORE starting the Gizmo)
1. Suppose you dropped a feather and a hammer at the same time. Which object would hit the
ground first? Why? ___________________________________________________________
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2. Suppose you could do this same experiment in an airless tube, or vacuum. Would this change
the results of the experiment? If so, how? __________________________________________
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Warm Up
Drag a pair of objects (no parachutes) to the top of the tower, one to each platform. Check that Air is
selected.
Click Play. The objects are now in free fall, pulled to Earth by the force of gravity.
1. What two objects did you drop? _____________________ _______________________
2. Did they fall at the same rate? ______ If no, which object fell faster? ____________________
3. Click Reset. Drop all possible combinations of objects (no parachutes).
a. Which object fell fastest? ___________________ Slowest? ____________________
b. Why do you think some objects fall faster than others? __________________________
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Activity A: Free Fall in a Vacuum: Click Reset. For Choose atmosphere, select Vacuum (no air)
Vacuum: a region of space with no air or any other matter
1. Hypothesis: How do you think objects will fall when there is no air to slow them down?
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2. Experiment: Drop the different objects from the top of the tower. What do you notice?
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3. Observe: Click Reset. Drop the watermelon and the ping pong ball from the top of the tower.
Watch the speedometers. They show each object’s speed in meters per second (m/s).
a. What do you notice? _____________________________________________________
b. What is the final speed of each object?
Watermelon ______________________ Ping pong ball _________________________
c. An object is accelerating if its speed is changing. What can you say about the
acceleration of objects falling in a vacuum?___________________________________
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