ball toss report

Grading Rubric:

Format of report is worth 1 point

Objectives are worth 2 points

Preliminary Questions are 1 point each, for a total of 3 points

Method is worth 2 points

Data is worth 3 points. You need the Data Table as well as the plots of position, velocity, and acceleration vs. time

Data Analysis is worth 3 points

Questions are 1 point per question, but for this assignment, Question 1 has 7 parts, worth total of 7 points, total overall of 16 points for questions

Conclusions are worth 3 points. The conclusions normally describe what you learned in the lab, and if it succeeded. Start by looking at the objectives of the lab. Were they satisfied? If they were, in the conclusions, state something like: In the ball toss lab, a basketball was tossed above a motion detector, and displacement, velocity, and acceleration were plotted vs. time. Each plot was studied. For the free fall section of each plot, a best fit curve, line, or statistics were used. A quadratic curve fit for the displacement plot, a linear curve fit for the velocity plot, and mean was used for the acceleration plot. Each fit was used to compare with the acceleration of gravity, and each parameter fit within a few percent error of the acceleration of gravity.

You can make it less technical, or longer or shorter.

The “Lab 4 Ball Toss ON 2 Report Template x” attached file is your template, with the data curves included. The “Notes Ball Toss Lab ” file includes the notes I took as we went through the lab. The Lab 4-ball_toss ” file is the description of the lab.

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Ball Toss
When a juggler tosses a ball straight upward, the ball slows down until it reaches the top of its
path. The ball then speeds up on its way back down. A graph of its velocity vs. time would show
these changes. Is there a mathematical pattern to the changes in velocity? What is the
accompanying pattern to the position vs. time graph? What would the acceleration vs. time graph
look like?

In this experiment, you will use a Motion Detector to collect position, velocity, and acceleration
data for a ball thrown straight upward. Analysis of the graphs of this motion will answer the
questions asked above.

Motion Detector

Figure 1

OBJECTIVES

 Collect position, velocity, and acceleration data as a ball travels straight up and down.
 Analyze position vs. time, velocity vs. time, and acceleration vs. time graphs.
 Determine the best-fit equations for the position vs. time and velocity vs. time graphs.
 Determine the mean acceleration from the acceleration vs. time graph.

MATERIALS

computer Vernier Motion Detector
Vernier computer interface volleyball or basketball
Logger Pro wire basket

PRELIMINARY QUESTIONS
1. Consider the motion of a ball as it travels straight up and down in freefall. Sketch your

prediction for the position vs. time graph. Describe in words what this graph means.

2. Sketch your prediction for the velocity vs. time graph. Describe in words what this graph
means.

3. Sketch your prediction for the acceleration vs. time graph. Describe in words what this graph
means.

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6 – 2 Physics with Vernier

PROCEDURE
1. Connect the Vernier Motion Detector to a digital (DIG) port of the

interface. Set the Motion Detector sensitivity switch to Ball/Walk.

2. Place the Motion Detector on the floor and protect it by placing a wire basket over it.

3. Open the file “06 Ball Toss” from the Physics with Vernier folder.

4. Collect data. During data collection you will toss the ball straight upward above the Motion
Detector and let it fall back toward the Motion Detector. It may require some practice to
collect clean data. To achieve the best results, keep in mind the following tips:
 Hold the ball approximately 0.5 m directly above the Motion Detector when you start data

collection.
 A toss so the ball moves from 0.5 m to 1.0 m above the detector works well.
 After the toss, catch the ball at a height of 0.5 m above the detector and hold it still until

data collection is complete.
 Use two hands and pull your hands away from the ball after it starts moving so they are not

picked up by the Motion Detector.

When you are ready to collect data, click to start data collection and then toss the ball

as you have practiced.

5. Examine the position vs. time graph. Repeat Step 4 if your position vs. time graph does not
show an area of smoothly changing position. Check with your instructor if you are not sure
whether you need to repeat the data collection.

DATA TABLE

Curve fit parameters A B C

Distance (Ax2 + Bx + C)
Velocity (Ax + B)
Average acceleration

ANALYSIS
1. Print or sketch the three motion graphs. The graphs you have recorded are fairly complex and

it is important to identify different regions of each graph. Click Examine, , and move the
mouse across any graph to answer the following questions. Record your answers directly on
the printed or sketched graphs.
a. Identify the region when the ball was being tossed but still in your hands:

 Examine the velocity vs. time graph and identify this region. Label this on the graph.
 Examine the acceleration vs. time graph and identify the same region. Label the

graph.

b. Identify the region where the ball is in free fall:
 Label the region on each graph where the ball was in free fall and moving upward.

Ball Toss

Physics with Vernier 6 – 3

 Label the region on each graph where the ball was in free fall and moving downward.
c. Determine the position, velocity, and acceleration at specific points.

 On the velocity vs. time graph, decide where the ball had its maximum velocity, just
as the ball was released. Mark the spot and record the value on the graph.

 On the position vs. time graph, locate the maximum height of the ball during free fall.
Mark the spot and record the value on the graph.

 What was the velocity of the ball at the top of its motion?
 What was the acceleration of the ball at the top of its motion?

2. The motion of an object in free fall is modeled by y = ½ gt2 + v0t + y0 where y is the vertical

position, g is the magnitude of the free-fall acceleration, t is time, and v0 is the initial
velocity. This is a quadratic equation whose graph is a parabola. Your graph of position vs.
time should be parabolic. To fit a quadratic equation to your data, click and drag the mouse
across the portion of the position vs. time graph that is parabolic, highlighting the free-fall
portion.

Click Curve Fit, , select Quadratic fit from the list of models and click . Examine
the fit of the curve to your data and click to return to the main graph.

3. How closely does the coefficient of the t2 term in the curve fit compare to ½ g?

4. What does a linear segment of a velocity vs. time graph indicate? What is the significance of
the slope of that linear segment?

5. The graph of velocity vs. time should be linear. To fit a line to this data, click and drag the
mouse across the free-fall region of the motion. Click Linear Fit, .

6. How closely does the coefficient of the t term in the fit compare to the accepted value for g?

7. The graph of acceleration vs. time should appear to be more or less constant. Click and drag
the mouse across the free-fall section of the motion and click Statistics, .

8. How closely does the mean acceleration compare to the values of g found in Steps 3 and 6?

9. List some reasons why your values for the ball’s acceleration may be different from the
accepted value for g.

EXTENSIONS
1. Determine the consistency of your acceleration values and compare your measurement of g

to the accepted value of g. Do this by repeating the ball toss experiment five more times.
Each time, fit a straight line to the free-fall portion of the velocity graph and record the slope
of that line. Average your six slopes to find a final value for your measurement of g. Does
the variation in your six measurements explain any discrepancy between your average value
and the accepted value of g?

2. The ball used in this lab is large enough and light enough that a buoyant force and air
resistance may affect the acceleration. Perform the same curve fitting and statistical analysis
techniques, but this time analyze each half of the motion separately. How do the fitted curves
for the upward motion compare to the downward motion? Explain any differences.

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6 – 4 Physics with Vernier

3. Perform the same lab using a beach ball or other very light, large ball. See the questions in
Analysis Question 1.

4. Use a smaller, more dense ball where buoyant force and air resistance will not be a factor.
Compare the results to your results with the larger, less dense ball.

5. Instead of throwing a ball upward, drop a ball and have it bounce on the ground. (Position
the Motion Detector above the ball.) Predict what the three graphs will look like, then
analyze the resulting graphs using the same techniques as this lab.

6. Repeat your quadratic and linear curve fits to the position graphs but use the time offset
option in the general curve fit dialog. Interpret the constant and linear terms of the quadratic
fit. What do they signify? What are the units of each term?

7. Repeat the linear fit to the velocity graph but use the general Curve Fit, . In that dialog,
choose the linear fit and enable the time offset option. Interpret the y-intercept of the linear
fit. What does it signify? What are its units?

Vernier Lab Safety Instructions Disclaimer

THIS IS AN EVALUATION COPY OF THE VERNIER STUDENT LAB.

This copy does not include:

 Safety information
 Essential instructor background information
 Directions for preparing solutions
 Important tips for successfully doing these labs

The complete Physics with Vernier lab manual includes 35 labs and essential teacher
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Name:

Physics 111 ON 2

October 1, 2020

Lab #4 Ball Toss

Objectives:

· Collect position, velocity, and acceleration data as a ball travels straight up and down.

· Analyze position vs. time, velocity vs. time, and acceleration vs. time graphs.

· Determine the best-fit equations for the position vs. time and velocity vs. time graph

· Determine the mean acceleration from the acceleration vs. time graph

Preliminary Questions:

1. Consider the motion of a ball as it travels straight up and down in free fall. Sketch your prediction for the position vs. time graph. Describe in words what this graph means.

2. Sketch your prediction for the velocity vs. time graph. Describe in words what this graph means.

3.Sketch your prediction for the acceleration vs. time graph. Describe in words what this graph means.

Method:

First we connect the Vernier Motion Detector to the Logger Pro and then connect that into the computer. Then switch the motion detector to Ball/Walk and place it on the chair in a place to protect it. After that on the laptop we open the ball toss files and then press collect data and hold the ball around 0.5m above the motion detector and toss it between 0.5m to 1m above the motion detector and hold it after catching the ball. Make sure your hands are not picked up by the motion detector.

Data:

Figure 1 Ball Toss (Position, Velocity, and Acceleration vs. Time)

Figure 2 Region Where Ball is _____________________________________

Figure 3 Region (Below) Where Ball is ______________________________________

Figure 4 _____________________________ Point Labelled

Figure 5 __________________________ Labelled

Figure 6 Ball Toss

(Position vs Time with Curve Fit, Velocity vs Time with Linear Fit and Acceleration vs Time with Mean)

Data Analysis:

1. Print or sketch the three motion graphs. The graphs you have recorded are fairly complex and

it is important to identify different regions of each graph. Click Examine and move the

mouse across any graph to answer the following questions. Record your answers directly on

the printed or sketched graphs.

1. Identify the region when the ball was being tossed but still in your hands:

1. Examine the velocity vs. time graph and identify this region. Label this on the graph.

See Figure _________________

2. Examine the acceleration vs. Time graph and identify the same region. Label the graph.

See Figure __________________

2. Identify the region where the ball is in free fall:

1. Label the region on each graph where the ball was in free fall and moving upward.

See Figure ___________________

2. Label the region on each graph where the ball was in free fall and moving downwards.

See Figure _____________________

3. Determine the position, velocity, and acceleration at specific points.

1. On the velocity vs. time graph, decide where the ball had its maximum velocity, just as the ball was released. Mark the spot and record the value on the graph.

See Figure ______________________

2. On the position vs. time graph, locate the maximum height of the ball during free fall. Mark the spot and record the value on the graph.

See Figure _____________________

3. What was the velocity of the ball at the top of its motion?

The velocity of the ball was _______ m/s.

4. What was the acceleration of the ball at the top of its motion?

The acceleration of the ball is _______ m/s/s.

2. The motion of an object in free fall is modeled by y= ½gt2+v0t+y0 where y is the vertical

position, g is the magnitude of the free-fall acceleration, t is time, and v0 is the initial velocity. This is a quadratic equation whose graph is a parabola. Your graph of position vs. time should be parabolic. To fit a quadratic equation to your data, click and drag the mouse across the portion of the position vs. time graph that is parabolic, highlighting the free-fall portion. Click Curve Fit, select Quadratic fit from the list of models and click. Examine the fit of the curve to your data and click to return to the main graph.

3. How closely does the coefficient of the t2 term in the curve fit compare to ½g?

4. What does a linear segment of a velocity vs. time graph indicate? What is the significance of the slope of that linear segment?

5. The graph of velocity vs. time should be linear. To fit a line to this data, click and drag the mouse across the free-fall region of the motion. Click Linear Fit.

6. How closely does the coefficient of the t term in the fit compare to the accepted value for g?

7. The graph of acceleration vs. time should appear to be more or less constant. Click and drag the mouse across the free-fall section of the motion and click Statistics.

8. How closely does the mean acceleration compare to the values of g found in Steps 3 and 6?

List some reasons why your values for the ball’s acceleration may be different from the accepted value for g.

Conclusions: