The effect of height on percent rebounds of dropped balls:

Introduction | Procedure | Picture | Data | Graphs | Errors | Conclusion | Return to research

 

Isabel Juliana and Connor Bruno

 

 

Introduction:

Background: When a ball is dropped, the height that it rebounds in never as high as the initial height because the kinetic energy lost when the ball hits the ground. The ball sometimes makes an audible sound and typically produces heat on impact, which causes it to lose kinetic energy. Making the height it rebounds to less than the height it started at. However, the amount of kinetic energy a ball has is slightly dependent on the amount of potential energy it starts with, which could be affected by the initial height of the ball.

 

Statement of question: The question that we chose to investigate is does the height that you drop various different balls from have an effect on the percent that the ball rebounds?

 

Variables:

Independent: The height the ball is dropped from

Dependent: The height the ball rebounds to/percent rebounds

Controlled: Person dropping the ball. Camera is in the same spot.

 

Hypothesis: We believe that the percentage of initial height a ball rebounds to will decrease as the initial height decreases. This is because there is more potential energy the height up the ball gets so the rebound has the potential to be greater.

 

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Procedure and design:

Procedure:

First we selected balls that are going to be dropped; we chose a red playground ball, a blue racquetball and a softball. To measure the height we then made a backdrop to drop the balls in front of, in the form of a huge ruler, we did a max of ten feet with line for every foot. Then we set up a video camera filming in slow motion and proceeded to drop all the balls from five different heights each and each height twice. Once we had filmed all the drops, we did video analysis to find the height that each ball rebounded. With that data we found the percentage by putting height rebound over initial height.

 

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Picture of set up:

 

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Data:

                   Initial Height Vs. Rebound height

ball

height (ft)

rebound (ft)

 Percent (%)

red playground

10

6.371

0.6371

 

10

6.366

0.6366

 

8

5.414

0.67675

 

8

5.337

0.667125

 

6

4.027

0.6711666667

 

6

3.93

0.655

 

4

2.724

0.681

 

4

2.736

0.684

 

2

1.255

0.6275

 

2

1.304

0.652

softball

10

3.171

0.3171

 

10

3.155

0.3155

 

8

2.571

0.321375

 

8

2.607

0.325875

 

6

1.946

0.3243333333

 

6

2.028

0.338

 

4

1.274

0.3185

 

4

1.261

0.31525

 

2

0.6778

0.3389

 

2

0.7008

0.3504

blue racquetball

10

6.507

0.6507

 

10

6.393

0.6393

 

8

5.325

0.665625

 

8

5.334

0.66675

 

6

4.108

0.6846666667

 

6

4.211

0.7018333333

 

4

2.836

0.709

 

4

2.877

0.71925

 

2

1.497

0.7485

 

2

1.404

0.702

 

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Graphs:

Chart

Chart

Chart

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Data File: text…Excel

 

Data Errors:

Uncertainty= (Max% -Min %) /2

Red playground ball uncertainty: .03%

Blue racquetball: .05%

Softball: .01%

 

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Conclusion:

After examining our data, we concluded that the percent of the initial height a ball rebounds is directly affected by the initial height. As seen in the graphs above the percent the ball rebounds to increases as the initial height decreases. It is not a large effect, but the trend can be seen across all three balls and as the height increases.

This experiment and results could have been more supported if we had done more trials and had a more stable camera setup for video recording making video analysis more reliable. Another potential limitation could have been having a person dropping the ball, we had the same person drop the ball and tried to drop them all the same but there is always a potential for human error. Overall, we are pleased with the results we got and find them fairly reliable for what we were trying to learn and establish.

 

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https://www.youtube.com/watch?v=ds7-VU4VrSo- This website really makes me think that bouncy balls can be very cheap and very effective

https://www.youtube.com/watch?v=pZlYl0l2lFs- This website is helpful to know how many types of ball bounce.

http://scienceline.ucsb.edu/getkey.php?key=2513- This website really gets into how balls bounce. Very helpful.

https://www.livestrong.com/article/147292-why-do-balls-bounce-differently/- This website is helpful in understanding how different ball bounce differently.

http://www.exploratorium.edu/baseball/activities/bouncing-balls.html- This website gives a great visual on how the balls change shape when bouncing.