Scioly.org

Don't forget that sand timers will have five to ten seconds of variability, depending on how fast the non sand timer tasks take. Also, I see this more as an engineering project than a science experiment. You have to design your device to overcome these random factors, however unfair, rather than .

Not that a problem like this wouldn't be frustrating.

I am using baking soda and vinegar to inflate my balloon. The balloon then hits a switch. The problem is that the balloon takes different amounts of time every other run. Are your reactions reliable? If not, what did you do to fix the problem?

illusionist wrote:I am using baking soda and vinegar to inflate my balloon. The balloon then hits a switch. The problem is that the balloon takes different amounts of time every other run. Are your reactions reliable? If not, what did you do to fix the problem?

Are you using the exact same amount of baking soda/vinegar each run? If not, measure it out and see if that helps. (Ours never varied by a more than a second, which was perfect.)

Also, have the balloon only need to expand minimally to push the switch. The more expanding necessary, the less reliable the timing will be.

We measure out the baking soda with a teaspoon, and the vinegar with a syringe; so I know that the amounts are consistent every time. I'll try minimizing the amount of inflation needed.

old wrote: The answer you seem to be suggesting is to arbitrarily carry a certain amount of extra buoyancy (how much? enough for a 0.1 M/S down draft or a 1/M/S updraft?) and hope you made the right choice.

You have a half hour to set up and practice. You can test the exact buoyancy of your balloon at that location during that time and fine tune the mass of your sign.

For that reason, I have made my mass adjustable. Basically I use clay to add or remove mass from my sign. There is a little container on the bottom of the sign to hold the clay.

illusionist wrote:For that reason, I have made my mass adjustable. Basically I use clay to add or remove mass from my sign. There is a little container on the bottom of the sign to hold the clay.

That's almost exactly what I did. I made the 'sign' out of a napkin, and folded it like an envelope so I could add mass to it as needed.

How much are you guys being able to lift? Is like 15-20 grams fairly reasonable?

Just saying, I think this is the balloon inflation task. The sign stuff should go over to the Sign Task thread.
So I'm going to carry this discussion over to that thread.