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Q & A: salt in bottle rockets

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Most recent answer: 09/15/2009
Q:
Hi My science class is making bottle rockets. I just finished reading your answer on how to make one and it was fantastic. I read some where that salt increases the specific impulse of a bottle rocket. Is that true? If so how much salt is needed? Thanks again and please respond soon!
- Kenny (age 14)
Staten Island NY USA
A:
Since the whole point of including water in a bottle rocket is to increase the amount of mass expelled by the pressurized air, it would seem like a good idea to make the water even heavier. Very salty water is denser than plain water. So if you use the same weight of salt water, that will leave a little more room for pressurized air. So I bet you're right- it should work better.

Mike W.

(published on 09/15/2009)

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