Science Buddies: "Ask an Expert"

It seems like it must be really important to use the SAME amount of aluminum foil for all of the boats, right? Otherwise, the masses of the boats would be different, thus having TWO variables at play with each boat: mass and volume. Don't we want only one variable to manipulate?

Assuming this to be the case, I'm trying to figure out if it's ok to manipulate the volume of the boat by folding the sheet of aluminum foil several times so that the walls of the boat are thicker, but the volume of the boat is smaller. Or are we also trying to keep the thickness of the walls constant; i.e. same number of layers of foil for all of the boats?

I'll probably have follow up questions but this is just to get the discussion started.

Hi chillipepper2525,

I'm assuming that you're working on the project described here:

https://www.sciencebuddies.org/science- ... boat-float

I agree with you that you want only one variable to manipulate in your experiment. In this project the one variable that you manipulate is the density of boats loaded with cargo. Because the mass of the pennies added to a boat to make it sink is much larger than the aluminum foil mass, small differences in the aluminum foil mass don't matter very much. But you can certainly make a variety of boats with the same mass of aluminum foil.

Because you'll measure the volume later, feel free to change to boat volume in any way you can. My suggestion is to try for a wide range of boat volumes. The boats just need to be leak-free.

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

A. Norman