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Buoyancy: Helium-Balloon Critical-Thinking Questions with Linked Answers
 © Donald Reinhardt, March 7, 2013

This is a useful, fun, educational exercise which promotes creative, critical and imaginative science thinking. There are no tricks here – just basic, clear ideas and experiments to think about. When you are finished review the answers by going to the link provided and check out the links to other buoyancy articles here to improve your understanding of buoyancy in air and water.

Instructions: Read the materials, methods and questions which follow.  Provide your full answer to the question and explain your reasoning and thinking. You might be more right than you think and there is no penalty for guessing what you think might or will happen.

Buoyancy Experiment Materials and Methods

Two balloons of the same mass (simple weight in this case) are filled with equal volumes of gas.
  1. If both balloons are released at the same moment and allowed to rise, what would we expect to happen over the course of time? Think and explain your answer.
2.    Assume the same balloons as indicated above.  One balloon was filled with helium gas and the other is filled hydrogen gas. Explain what happens when the balloons are released simultaneously.
3.     Assume that the ground air temperatures are equal when helium-filled balloons are released on a cloudy day and other totally-similar balloons are released at the same location on a bright, sunny day. What behavior or observations would you expect regarding these balloons as the balloons rise?
4.     It is a nice, bright and clear day and two identical helium balloons are released simultaneously. One balloon is pure white and the other intense black. What do you expect to happen over the course of the next hour and why?
5.     When helium-filled balloons are released into the air indicate those conditions or circumstances which will cause these balloons to return back to earth.
Answers to these questions are linked here