Balloon Rockets: What a drag!

Updated: January 1, 2024

The balloon rocket is a classic science experiment, but this activity often ignores a very important force that is part of real rockets: drag! Hook students with a question: which will travel faster, a smaller or larger balloon? Students will likely be surprised that the smaller balloon actually travels faster and gets to the end of the first! Why is this happening? First, students will explore the thrust force and how this moves a balloon through the air. Next, students will be introduced to drag forces with a series of demonstrations and discussions that involve dropping objects of various sizes and weights. Students generally learn the idealized law that all objects fall at the same rate, but this ignores air resistance. These demonstrations will push their thinking and help them understand the role of drag based on the influence of surface area. Finally, the students will return to the balloon rocket activity and apply their knowledge of air resistance and thrust to optimize a balloon rocket that travels up to the ceiling!

Balloon Rockets: What a Drag!