Balloon Rockets: Newton’s Laws and Energy Lab

Description

The conclusion/analysis questions will be easier to answer if the students have a grasp of Newton’s Second and Third Laws of Motion, a working understanding of free-body diagrams, and how to set-up an appropriate number-scale for the axis on a graph. There will be some basic calculations involving Newton’s Second Law, but if they can divide and multiply, they should have no problem with the math.

I typically do this lab over 2 days, assuming each class is roughly 55 minutes in length. By the end of the first day, I try to have most of the groups get most of their data down. If you wanted to squeeze this into a single day, I would split them up into groups, give each group a different set of fabricated data, and have the groups complete the rest of the lab together. This would give them the conceptual essentials, without the hands-on engineering aspect.

For this lab, you will need the following materials:

• Balloons with ridges (bumps). I get mine from Party City. They have good quality. But any long balloon will do, if you can’t find the balloons at Party City.
• Fishing line (about 20 feet or 6 meters approximately; the thinner, the better)
• Stopwatch (or smartphones, depending on your classroom rules)
• Colored pencils for the line graph (or use pen and pencil to differentiate instead)
• Scissors for cutting the paper, straws, fishing line, etc.
• Masking tape (for the floor starting line) & Scotch tape (to attach balloons)
• Straws (if bendable straws, cut off the flexible part)
• Sheets of paper (optional, if time permitting)
• CRC Silicone Spray (helps to reduce friction, but not necessary)
• Tape measure (metric if possible)
• Roll of pennies
• Calculator (graphing calculators not necessary)

Tips and Hints for the Lab:
• Have everything prepped ahead of time and do a dry-run of the lab. But this should go for every lab activity you do. There may be some aspects that you may want to customize, edit, or exclude. Nobody knows your students better than you.
• Make sure the fishing line is level before starting the races. Lube the fishing line with the CRC silicone spray lubricant before the start of each class. Just spray some on a paper towel and run it up and down the line. This stuff works wonders for reducing friction.
• I use hooks screwed into the wall for this lab. This is useful since I do the lab every year. Also, do not set up the fishing line until you are ready to race. Otherwise, many students just seem to walk into it by accident and get tangled up. Funny the first time it happens, though! But annoying after that.
• Have as many fishing lines set up as you can. This will help eliminate idle time for students as they wait to test their balloons.
• To get the most accurate results, consider timing the balloons yourself. Many students will try to shave a couple of seconds off their times in order to have the fastest balloons.
• If a group finishes faster than some of the others, make it mandatory that they use a piece of paper to modify the aerodynamics of their balloon. Then if they achieve better results, have them use the new results in place of the old data.
• After the lab is done, especially for the balloon race section, give yourself a few extra minutes and have the students clean up the area of balloon debris. Even though the Party City balloons are solid quality, they can (and do) burst. Consider having a student remind you when there is 5 minutes left in class for cleanup.
• Let other staff members know you are planning on using balloons and will be popping them. Unfortunately, in this day and age, balloon pops might be mistaken for gunfire.
• Make sure that none of your students have an allergy to latex balloons.

Newtons second law of motion, Newton third law of motion, balloon rockets, equal and opposite reactions, F=ma, kinetic energy, potential energy, free-body diagram, net force, equilibrium, balanced forces, average acceleration, action force, reaction force, distance vs time graph, inverse mathematical relationships, direct mathematical relationships, energy lab