Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
[Note: The purpose of these questions is to activate prior knowledge and get students thinking.
Students are not expected to know the answers to the Prior Knowledge Questions.]
1. Suppose you dropped a feather and a hammer at the same time. Which object would hit the
ground first? Answers will vary. [The hammer would hit the ground first.]
2. Imagine repeating the experiment in an airless tube, or vacuum. Would this change the
result? If so, how?
Answers will vary. [In a vacuum, both objects would hit the ground at the same time.]
Gizmo Warm-up
The Free-Fall Laboratory Gizmo allows you to measure the motion of an
object in free fall. On the DESCRIPTION tab, check that the Shuttlecock
is selected, the Initial height is 3 meters, and the Atmosphere is Air.
1. Click Play ( ) to release the shuttlecock. How long does it take to
fall to the bottom? 0.90 seconds
2. Select the GRAPH tab. The box labeled h (m) should be checked,
displaying a graph of height vs. time. What does this graph show?
The height decreases over time.
3. Turn on the v (m/s) box to see a graph of velocity vs. time. Velocity is
the speed and direction of the object. Velocity is also referred to as
instantaneous velocity. Because the shuttlecock is falling
downward, its velocity is negative.
Does the velocity stay constant as the object drops? No
4. Turn on the a (m/s/s) box to see a graph of acceleration vs. time. Acceleration is the rate at
which the velocity changes over time. What does this graph show?
Acceleration starts at about -10 m/s/s, but gets closer to 0 as the shuttlecock falls.
This study source was downloaded by 100000808701186 from CourseHero.com on 02-19-2022 08:23:04 GMT -06:00
2019
https://www.coursehero.com/file/70189294/FreeFallSE-Keypdf/
, Get the Gizmo ready:
Activity A:
Click Reset ( ).
Falling objects
Select the DESCRIPTION tab.
Question: What factors affect how quickly an object falls?
1. Observe: Drop each item through Air from a height of 3 meters. Record how long it takes to
fall below. For the tennis ball, try to click Pause ( ) when it hits the ground.
Shuttlecock Cotton ball Tennis ball Rock Pebble
0.90 s 1.36 s ~0.81 s 0.79 s 0.80 s
2. Form a hypothesis: Why do some objects fall faster than others? Hypotheses will vary.
3. Predict: A vacuum has no air. How do you think the results will change if the objects fall
through a vacuum?
Predictions will vary.
4. Experiment: On the Atmosphere menu, select None. Drop each item again, and record the
results below.
Shuttlecock Cotton ball Tennis ball Rock Pebble
0.78 s 0.78 s 0.78 s 0.78 s 0.78 s
5. Analyze: What happened when objects fell through a vacuum?
Every object took the same amount of time to fall to the ground.
6. Draw conclusions: Objects falling through air are slowed by the force of air resistance.
Which objects were slowed the most by air resistance? Why do you think this is so?
The cotton ball and shuttlecock were slowed the most by air resistance. They were slowed
the most because they were the lightest and largest objects.
(Activity A continued on next page)
This study source was downloaded by 100000808701186 from CourseHero.com on 02-19-2022 08:23:04 GMT -06:00
2019
https://www.coursehero.com/file/70189294/FreeFallSE-Keypdf/
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