Tennis Balls - bounce height open vs unopened can

[deleted-320661]

Hello

I need some help (helping my son )setting up the variables for Science Fair projects. He is comparing the bounce of tennis balls: new unopened cans of tennis balls vs. opened cans of tennis balls (first testing will be with balls opened for 24 hrs....second testing will be balls opened 7 days prior).

The hypothesis is:
If pressurization of the tennis balls inside the cans keeps the tennis balls fresh, then the height of the bouncing ball from a newly opened can will be greater than a ball that has been opened previously for 24 hours or if opened previously for 1 week.

We have to travel overseas, so need to finish project a bit sooner than the other kids. (with 12 days).

Thank you for your help
Nina

[norman40]

Hello Panina12,

Are you asking about the independent and dependent variables in your experiment?

If so, an independent variable is something the experimenter changes in order to observe a response in a dependent variable. For example, if I increase the air pressure in a balloon, I expect an increase in the diameter of the balloon. Here, the independent variable is air pressure and the dependent variable is diameter. Some additional information on variables can be found here:

https://www.sciencebuddies.org/science- ... bles.shtml

Your hypothesis clearly states the item that you’re changing in your experiment and the response you expect to see. The item you’re changing is your independent variable. The response you expect from changing the independent variable is your dependent variable.

I hope this helps. Please post again if you have more questions.

A. Norman

[deleted-321403]

The article has been really helpful.

[deleted-320661]

Hi Norman

Thank you! I read later the article, but could not figure out how to update my question.

I figured out that:

Independent Variables: Are the Tennis Balls (the unopened cans, the 24hour open cans and the 1 week open cans.
Dependent Variable: The Bounce (How height is the ball going to Bounce) because of the difference in pressurization.
Control Variable: Would be the Height from which the balls are thrown.

I will have him create a table to compare all three bounces from two different heights, with 2 different brand of balls, with 3 different pressurization.....Oh my head hurts!

I think we should compare by height, regardless of the brand....so I would have two tables.

What do you think?

Thanks,
Panina

[norman40]

Hi Panina12,

You’re on the right track with your variables. I agree with you on the dependent and controlled variables. But I would say that your independent variable is the length of time that the tennis ball cans have been open (zero time for the unopened can, 24 hours, 1 week).

If you include two brands of tennis balls in your experiment, then the brand is a second independent variable. And if you change the height from which the balls are dropped, the height is a third independent variable (and no longer a controlled variable).

From your description it seems that you’ll have quite a bit of data. One way of organizing the data is to put the data for each brand of ball into separate tables. Then you could tabulate or chart the average bounce heights for the different “can open” times. Another table or chart could shown the average bounce heights for the different brands.

I hope this helps. Please post again if you have more questions.

A. Norman