Balloon Rockets: What a Drag!
Updated: November 16, 2024
Type: Science Practices, Forces & Motion
Grade Level: 6 - 8
In the classic balloon rocket challenge, students generally walk away with the misconception that a larger balloon will travel faster due to a greater thrust force. This is inaccurate! In this video, I will demonstrate a lab centered around scientific inquiry that accounts for a force often missing from this lesson–drag! Watch below and then scroll down for the lab handout.
Teachers will be guided through a scientific inquiry lab that starts with a demonstration on whether a larger or a smaller balloon will reach the end of a string first. They will be shocked to find that the smaller balloon actually travels faster and gets to the end first! Why is this happening? First, we will discuss thrust and how to demonstrate the thrust force resulting from the air leaving the balloon. Next, I will introduce 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 towards the ceiling!
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