Name ____________________________________ Date __________________
Falling Objects
ESSENTIAL QUESTIONS
What is the acceleration due to gravity of a falling object?
Do objects fall at the same rate? If not, what affects the acceleration of a falling object?
OBJECTIVES
In this experiment, you will



Use a Motion Detector to measure position and velocity.
Produce position vs. time and velocity vs. time graphs.
Analyze and explain the results.
MATERIALS
computer
Vernier computer interface
Motion Detector
ring stand
metal rod
right-angle clamp
basket coffee filter
3 books
meter stick
motion
detector
interface
Figure 1
Middle School Science with Vernier
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Falling Objects
PROCEDURE
1. Set up the apparatus as shown in Figure 1.
a. Place two books on the base of a ring stand to keep it from falling.
b. Use a right-angle clamp to fasten a metal rod to the ring stand.
c. Fasten a Motion Detector under one end of the rod. The Motion Detector should face
down and be parallel to the floor.
d. Move the right-angle clamp, rod, and Motion Detector to the top of the ring stand.
e. Use a piece of tape to mark a spot on the ring stand that is 25 cm below the right-angle
clamp.
f. Place the ring stand, with the Motion Detector attached, at the edge of your lab table. The
Motion Detector must extend 30 cm beyond the table edge.
2. Connect the Motion Detector to the LabQuest 2 interface. Set the Motion Detector switch the
picture of a ball.
3. Open Logger Pro from the desktop of the computer. (You should see a box with Position data
in meters under the data table, as well as a position vs time and a velocity vs time graph.)
4. Set up data collection parameters.
a. Choose the Experiment Menu and the “Data collection…” option.
b. Change the duration to 1 second and the sampling rate to 20 samples/ second.
5. Collect data for a falling coffee filter.
a. Hold a basket coffee filter with the open side facing up at a position of 0.25 m from (at the
0.25 m mark with tape on the ring stand) and directly below the Motion Detector.
b. Choose the Experiment menu and the “Zero…” option.
c. Click
to begin data collection.
d. When you hear sound coming from the Motion Detector, allow the coffee filter to drop
straight down.
6. Store data for a good coffee-filter run.
a. Observe the graphs. Repeat the coffee-filter drop, if necessary, until you have “smooth”
curves for both graphs.
b. Choose Store Latest Run from the Experiment menu to store your good run. Your coffeefilter run will be stored as Run 1.
7. Repeat Step 4 using a book and then any other objects of your choice.
a. Observe the graphs. Repeat the book drop, if necessary, until you have “smooth” curves
for both graphs.
b. Choose Store Latest Run from the Experiment menu for each additional object once a
satisfactory curve is observed.
8. Observe the graph. Click and drag the cursor over the section of the graph that displays a
smooth curved line.
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Middle School Science with Vernier
Name ______________________________________________ Date ___________________________
9. Determine all object’s acceleration rate by choosing the Analyze menu and “Linear fit”
a. Record the “m” value (which is the slope of the curved line between the selected points) as
this is your object’s acceleration.
10. Determine the velocity at the highest part of each object’s velocity vs. time curve.
a. Choose the Analyze menu and “Examine”. Move the mouse pointer to highest point on the
velocity vs. time graph. Record the velocity at this point for the coffee filter and book.
b. Note and record the shape of the curve in the region of the maximum velocity.
11. Save graphs and data showing your results by choosing the File menu and “Save as…”.
a. Save a copy to EACH student’s file space.
DATA
Table 1: Acceleration rates for various falling objects.
Run
Object
1
Coffee Filter
2
Book
Mass (g)
Acceleration (m/s/s)
3
4
5
Table 2: Maximum velocity of coffee filter and book.
Falling coffee filter
Maximum velocity
Falling book
m/s
m/s
Curve shape in
maximum region
Middle School Science with Vernier
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Falling Objects
ANALYZING THE DATA
Consider the coffee filter and book for the following questions.
1. Which object fell faster? Why?
2. How are the two position vs. time graphs different? Explain the differences.
3. How are the two velocity vs. time graphs different? Explain the differences.
4. Compare the maximum velocities of the filter and book.
5. Which object was falling faster when it landed? Why was it falling faster?
6. For which object is air resistance more important? Why does air resistance affect this object
more than the other object?
Velocity (m/s)
7.
0
1
2
Time (s)
3
On the graph to the left, sketch a velocity vs.
time curve for an object that is released at
0.5 s, falls with increasing velocity until
1.5 s, falls at constant velocity from 1.5 s to
3.0 s, and lands at 3.0 s. An object that falls
at constant velocity is said to have reached
terminal velocity.
8. Did either of your objects reach terminal velocity? If so, which one? How do you know?
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Middle School Science with Vernier
Name ______________________________________________ Date ___________________________
Consider ALL of the objects you measured falling for the following questions.
9. Did all objects accelerate at the same rate as they fell? Why or why not? (Consider how big of
a difference in numbers is a “significant difference”.)
2. IF there were objects falling at approximately the same rate, what is the average value of
acceleration due to gravity of these objects? (hint: you must calculate this)
3. Did mass have any effect on the rate of acceleration? Explain using specific examples of data.
4. Did anything else influence the rate of acceleration? Explain using specific observations.
Middle School Science with Vernier
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Falling Objects
CONCLUSIONS
What is the acceleration due to gravity of a falling object?
Do objects fall at the same rate? If not, what affects the acceleration of a falling object?
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