Does the pressure in a basketball effect the foul shot?

[Casey258]

I am 12 years old and I am doing my first ever science fair experiment. It is about the effect that air pressure has on your shot. We are using two basketballs, one with 1/2 of the regualtion air pressure and one that is pumped to regulation. We are shooting from the foul line only, this is our control. I have started to take documentation while having classmates shoot the foul shots. I will also be having some of the girls basketball team from our local High School do the same. Most of the people are shooting at the same % with both basketballs, or they are shooting better with the flat ball. I am having a hard time finding other science projects online like mine. I need to document others findings. Most of what I am finding is about rebound with different pressure in the ball.
Second the physics of it says that with less air their will be less molecules to bounce around inside the ball?? Is that right? I am stuck on how to procede, and how to tie in my findings with this experiment. I think that the reason they are making more baskets with the flat ball has to do with less pressure so less bounce. This makes the ball drop into the basket.
Help please. I do not know how to move forward.

[rmarz]

Casey258 - I think you have chosen a very difficult hypothesis to prove through experimentation. The largest variable you are contending with is the variability or repeatability of the 'shooters' in this experiment. Even if you had an NBA superstar at the line, it would be a difficult task to take enough observations to begin to prove the hypothesis one way or another. Theoretically, perhaps the best way to perform this experiment would be with a precise, mechanical ball launcher whose repeatability could be perfectly designed into the mechanism. My guess is that either ball, fully inflated or partially inflated, would show the same results for accuracy once calibrated with this theoretical mechanical launcher. Certainly the softer ball would show more deformation during launch, but once accounted for, would still probably go through the hoop consistently. I don't want to dissuade you from the experiment, but perhaps a better experiment might have to do with the 'rebound' characteristics or handling effort of the hard versus soft ball. Your observation of more soft balls going through the hoop is very likely due to rebound characteristics bouncing off the rim (another issue of variability of the shooter). The soft ball may be more 'forgiving'. With the mechanical launcher, the design would be such that there would be no contact with the rim, 'just net'. These are just my thoughts, as I think there are few of us experts able to handle this question very well. You will likely to get similar answers that are driven by statistics, physics and control of variables issues.

Rick Marz

[Casey258]

Thank you I have one problem with this though. The experiment has been approved by teacher and I am 1/2 through the experiment. That being said how do I proceed ?

[rmarz]

Casey258 - I suggest that your new hypothesis might be that "the softer ball" will drop through the net more often due to the reduced rebound energy that otherwise might have caused the ball to be deflected off the rim. It's not perfect, but you may be able to tell a story. Perfect 'swishes' should be counted separately in the data. The larger your sample size (number of thrown balls) the better correlation you might achieve in your results. You are still dealing with many uncontrolled variables, and that caveat should be mentioned in your experiment description. You should collect your data (by individual shooter) to include total attempts made and total balls sunk, noting how many sunk actually touched the rim versus perfect 'nothing but net' balls for the most meaningful study. Collect the data for each ball (hard and soft). You can present a summary table with percentages and grand totals. A meaningful trend may develop when you analyze the data. Good luck.

Rick Marz

[Casey258]

Great Thank you !!