Science Fair Project 2007

[URY914]

Which volleyball will bounce higher???

Manipulated Variable:
Each volleyball has been filled with a different gas.

Responding Variable:
The height to which the ball bounces

Constant Variable:
The ball release apparatus will be the same throughout the experiment.
Each ball will be released from the same height.
The volleyballs are the same brand and size
The pressure of the gas will be constant in all the balls.

The balls are filled with 5 pounds of compressed air or helium or nitrogen.

The balls were dropped 10 times each.

This is our release device. Shop vac when turned on would hold the ball, when switched off the ball would drop.

OK, all you smart guys, which ball bounced higher???

Helium?
Nitrogen?
Compressed air?

[slodave]

I say:

Compressed air

Dave

[URY914]

Oh yea, your answer has to explain why you think so.

[slodave]

Mythbusters did something like this with footballs. They did not use nitrogen, but the air filled balls went farther. I tried looking this up on Google and just fried my brain with one of the answers I read. I have no idea why, but I still say air.

Dave

[BRPORSCHE]

I am going to have to go with compressed air also. Helium and Nitrogen are both lighter then air, so when the ball hits the ground there arent enough vibrations for it to bounce. I sound like I am speaking hogwash.

[Don Plumley]

The ball with compressed air is heaviest, hence it will fall with more force (F is proportional to M) hence it will rebound with more force, thus rebound higher. I think.

[HardDrive]

I'm going with air. My scientific method involved darts and post it notes with Helium, Nitrogen and Compressed air written on them.

[URY914]

Well here are the results...

It was the compressed air but only by the slimmest amount and you would really never know if someone slipped a helium ball into the game at halftime. I believe if we used beach balls which held a greater volume of gas the results would be more varied.


Don is correct, the heavier ball bounces higher because it falls with a greater force. The ball acts as if it were a spring as it is hitting the ground.

This is for my 5th grade daughter. The projects are being judged this week. If you finish in 1,2, or 3rd place you advance to the regional contest and from there the state level. We're hoping for a solid 4th place finish.

[red-beard]

The issue is mass versus drag. If there were no air resistance, then the balls would all bounce the same. The extra mass of the air filled ball means the ball starts with more energy. It loses the same energy due to rebound and air resistance as it falls, it then will be able to rebound to a higher level.

[Grady Clay]

“
Manipulated Variable:
Each volleyball has been filled with a different gas.
Three balls?

Responding Variable:
The height to which the ball bounces

Constant Variable:
The ball release apparatus will be the same throughout the experiment.
Each ball will be released from the same height.
The volleyballs are the same brand and size
The pressure of the gas will be constant in all the balls.
What is the precision of the pressure measurement?
The temperature is constant

The balls are filled with 5 pounds of compressed air or helium or nitrogen.
I would use Argon in place of air. With room air, you have uncontrolled water content. You might borrow a tank from a welding shop.
He - 0,1786 g/L @ 0°C, 101.325 kPa.
N2 – 1.251 g/L “
Ar – 1.784 g/L “

The balls were dropped 10 times each.
I would do this more times depending on the “placebo” experiment below.

This is our release device. Shop vac when turned on would hold the ball, when switched off the ball would drop.

How are you going to measure the height of the bounce? How accurate is that measurement. How repeatable are the measurements? A useful way to measure this is to use a video camera to view the ball at the apex of the bounce and a meter stick in the background. Then view the ball frame-by-frame.

The person measuring the height should not know what gas is in the ball or what order the drops are. Double blind.

A useful “placebo” experiment would be to do the experiment all the same gas in the three balls. Number the balls. Is there any difference between the balls?

Another useful experiment is to run the experiment with the pressure from 4.0 to 6.0 psi and determine the effect the pressure has. This will tell you how sensitive the experiment is to pressure. You could also do this with temperature.

For an 11-year old, the most useful things to focus on might be;
Effect of bias.
Accuracy of measurements (including the effect of parallax with the camera).
Why you do many repetitions.

A useful way to analyze the data is using your Post-Its on a number line marked with appropriate equal intervals. For example, if 5.0 cm intervals are appropriate and you had three results; 2674 cm, 2672 cm and 2674 cm. In the interval between 2670 and 2674 (inclusive), you would paste on the Post-Its to build a vertical bar. With enough data points, this generates an understandable histogram. You can talk about the average (mean) and how sharp or flat (standard deviation) in a visually understandable form. Using Post-Its allows your student to build the curve data point by point.


The wonderful thing about science fair is it allows you to include so many important things in a fun project. In 1st and 2nd grades my youngest did; “”Do un-stretched rubber bands shoot farther than pre-stretched rubber bands?” and “Do big water balloons go farther than little ones?”

Best,
Grady

[URY914]

Grady,

All good points, thanks.

Yes, we used three seperate new balls. We used compressed air because that is the standard that all balls are filled with for play. The idea for the project came from a conversation I had with my daughter at a college v-ball match. At half time the refs collect the balls and hold them until the second hald starts. My daugher asked me why they did this. I said so someone doesn't switch one of the balls out with one filled with helium in order to throw off the other team. This got the wheels in her head working and she said lets find out if it would make a differance.

We were inside so no air flow or temp changes.

To measure the bounce heights, we ( I mean she) set up a 10' steel bar with marks at every 2". I viewed the bounce while standing on a chair so my line of site would be even with the top of the bounce. I was several feet away from the drop zone. We had a video camera with us but after recording a few bounces we saw the camera would not focus on the ball fast enough and the ball was a blur. If we were to change any one thing it would be the method of measuring the bounces.

Our previous project was the strength vs weight of carbon fiber and fiberglass. She finished 4th with that one.

[dad911]

Heavier ball would fall faster, but would use more energy to lift (Energy=Mass x Distance), so I would think that would wash.

I would think air pressure would be the referees concern.

[IROC]

Originally posted by URY914
It was the compressed air but only by the slimmest amount ...

What was the difference? From what height were the balls dropped and how much higher did the compressed air ball bounce?

Mike

[URY914]

Originally posted by IROC
What was the difference? From what height were the balls dropped and how much higher did the compressed air ball bounce?

Mike

The balls were dropped from 15' MOL. I don't have the exact distance with me here at work.

Air average bounce= 88.7"
Nitrogen= 85.7"
Helium= 85.7"

[Grady Clay]

Some more thoughts.

Can you get the video camera to fix the focus on the scale in the background?

Discuss what would happen if the ball lands on the fill valve. What would happen if you put the fill valve at the vacuum?

How about weighing each ball?

Data recording:
Use a real bound scientific notebook with numbered pages. As an alternative, use a bound “composition” book and number the pages. Use permanent ink. If you make a mistake, strike-out the error but leave it readable. If you want to strike out a page, put horizontal lines at the top and bottom and a diagonal in between.

When you use computer files, digital images, etc. glue paper copies in your notebook. Keep everything organized. Maintain computer file back-up.

This is a good opportunity to point out that the language of science is mathematics. Every measurement has a number and a unit. Fifth grade might be a good time to talk about unit conversion.

With science fair projects it is desirable to use standard metric units and notation.


For Pelicans with older students, these kinds of elementary school level science fair experiments are very appropriate in high school. A typical problem in middle and high school is the student wants to do a too complicated experiment. You want a very simple experiment that is very easy to do many times. You then apply more advanced research, planning, process, analysis and presentation.

You will find the “finish” of science fair projects are very good in the early grades and decrease through the grades until middle school. The high school presentations tend to get much better.



Off & on for the past 18 years I have supervised projects. Mostly with a high end 9th grade Science Research class.

The general sequence I use is:
Decide on a project
Research the field and write a Review Paper
Devise a plan (& hypothesis)
Write an experimental procedure
Do the experiment
Analyze the data and come to a conclusion
Combine Review Paper and results into final paper
Write an Abstract
Prepare presentation
Present results

At each step there us usually a lot of review and revising. It isn’t unusual to go back several steps or even start over. At elementary level many steps are invisible. By high school each (and more) are graded milestones. With the 9th grade program, the student’s Abstract is published by part of the IEEE.

One of my former 9th grade students is VP of Google.

Best,
Grady

[Seahawk]

Grady,

Could not be better advice (but you knew that). My only add is for others to take into account the amount of TIME represented in your post.

My son just finished 2nd in the local Science Fair and gets to move on. His project was the difference in both velocity and impact between regular paint balls and fozen paint balls.

Since my wife is a science geek (has been a judge), we followed your premise. What we did not account for were the ambiguities in the experiment and the need to re-test/shoot.

Time.

[URY914]

Here are some more details...

When we set the balls on the end of the vacuum, we positioned the valve stem on the top of the ball. Consistancy was the goal.

We marked the measuring stick in feet and inches because I didn't have a tape measure that was in meters/centimeters. She later converted the measurements to metric.

We didn't think of weighing the balls but that would have been another piece of data that would have been nice to have.

She used a composition book for recording and note taking. we dated and recorded every entry. Including notes from the very first parent's meeting we had at school.

The video camera had problems with the auto focus when the ball entered it's field of vision. We should have use a piece of 4 x 8 plywood marked with the measurements. This would have filled the complete view finder of the camera. We were limited by the amount of time when had in the building we were using so we didn't have the time to do a dry run with the camera. Next time will be different.

She had to post all the data and pictures on a presentation board and be able to be interviewed by the judges. She'll find out in a few days how she did. I will post the results (as any proud father would).

Paul

[M.D. Holloway]

We need pics of a girls university volley ball team to make an accurate determination.

make that a beach volley ball team from Brazil intead. Yep, that would settle this bet!

[URY914]

Originally posted by LubeMaster77
We need pics of a girls university volley ball team to make an accurate determination.

make that a beach volley ball team from Brazil intead. Yep, that would settle this bet!

I've always said all threads here go one of two ways, politics or sex. This stupid comment once again proved my point.

[Grady Clay]

Seahawk,

You are correct about the amount of time. Science fair is a multi-week project.


The course I teach lasts almost two semesters. It starts after
about two weeks of school and after we have an idea of who
will succeed. The candidates for this course come from the 18
high end 9th grade “Physical Science H” classes with about 370
students (the school has 3600 students and is among the top
in the nation). We typically have about 9-12 freshman for
the “Science Research H” course. I did 32 one year but that
taxed my time. I’m a volunteer and 60-hour weeks exceeded
my comfort level.

I consult, read and correct papers, find resources and solve
problems. Our 14-year olds are fantastic but occasionally they
get stuck. A little help and they are off and running. The most
difficult part is convincing them to do an elementary level
project. They all want to do world class nuclear research or find
the cure for AIDS. The goal is to do a 3rd grade experiment but
apply undergraduate level process. As sophomores they can
then tackle any subject. Some we connect with university research.

This is an independent study course and we only meet in the
normal classroom or at lunch. It is an “Honors” course with five
points on a 4-point scale. Most of these kids end up taking a
handful of AP cources.

Virtually all of these students go to the regional and state science
fairs. Each year someone or few go to the Intel ISEF. I have paid
for several travel and lodging expenses and been a chaperone.

The course basically ends in April with the presentations to the
Colorado-Wyoming Junior Academy of Science. Heady stuf
f for 14-year olds to stand in an auditorium of peers, college
professors and grad students.

About the only things after the presentation are writing the
abstract, turning in the final paper and a future experiment
proposal. Of course, many repeat the course as sophomores
and some all four years. Some of these kids graduate to
Harvard, MIT and Stanford after only three years of HS.



Paul, what material did you (parents) get and what was given
to students? What was the start-to-finish time span?

Clearly your daughter (and you) enjoyed the project. While she
is still enthusiastic, plan for next year.

Science fair is touted to teach the “Scientific Method.” It is much
more than that. It is about organization, reading, writing,
studying, research (even in 3rd grade), mathematics, real
science and more. It fosters clear thinking and realizing that
you can do anything. When it is fun, you can
introduce all sorts of advancement.

Paul, many high schools and universities have an ultrasonic position detection system.
This is very portable and easy to use and calibrate. Ask your high
school (the one your daughter will attend) if they have one.
Start with the head of the science department.



Here is my youngest kid’s first grade rubber band experiment from 15 years ago.



The display has suffered some and is faded. The only thing
missing is the paper scale that continued from the bottom of
the results scale to zero (about 3 feet). If anyone wants I can
email better detail.

See how the Post-It histogram worked. I think we started with
40 data points and ended up with 60. I think we repeated the
experiment about six times. It probably should be more for
someone's MS or HS project.

Shooting rubber bands, launching water baloons and
dropping vollyballs is fun. Use it.

Best,
Grady