Falling Balloons (Jake Dickerman)

Author

Jake Dickerman

Principle(s) Illustrated

Human beings do not breath out pure CO₂. In fact, the majority of the gas we breath in and out is nitrogen gas. We breath in approximately the same amount as we breath out.
Buoyancy is an upward force determined by calculating the weight of displaced fluid. That means that if you use a denser fluid to fill something, the buoyant force will have less of an impact on the object's motion than if you used a less dense fluid.

Standards

Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly. (HS-LS1-3)
Changes of energy and matter in a system can be described in terms of energy and matter flows into, out of, and within that system. (HS-LS1-5), (HS-LS1-6)
(I don't know if this fits into a specific DCI, but one thing I do want students to understand after this lab is the composition of the atmosphere and how that impacts gas flow between the atmosphere and the biosphere)

Questioning Script

Prior knowledge & experience:

When people exhale, they breath out carbon dioxide
Dry Ice is made out of CO₂

Root question:

Three balloons are inflated. One with a balloon pump (atmospheric), one with lungs, one with the sublimation of dry ice. Which will fall fastest and why?

Target response:

The dry ice balloon should fall fastest, since CO₂ is denser than either atmospheric air or than the air out of your lungs. The air from your lungs and the atmospheric balloon should both fall at a similar rate.

Common Misconceptions:

All the gas that a human breathes out is CO₂ - therefore the dry ice balloon and "blown out" balloon should drop at the same rate.

Photographs and Movies

Put all photos in the class photo album and reference here.

Put all movies in your own Youtube account. Make sure that the account is set for public viewing. Insert the Youtube videos here.

Applications to everyday live

An understanding of breathing in nitrogen gas explains "the bends" - a real problem that divers experience. We can also understand from this how the most important aspect of pressurizing an astronaut's suit is the nitrogen gas, not the oxygen gas.

References

References (give the title of the page and insert a link. Don't just paste a URL)