Have you ever wondered how your marshmallow propeller can shoot marshmallows so far and fast? It’s all thanks to a super cool thing called “propulsion.” Propulsion is the force that moves objects, like your marshmallow, forward.

In your marshmallow propeller, the propulsion comes from the air pressure. When you pull back the plunger, you’re creating a space for the air to get squished. The more you pull, the more air gets squeezed into that small space. That air really wants to escape, and when you let go of the plunger, it rushes out, pushing the marshmallow forward. Whoosh!

Propulsion is used in many different ways, like in rockets that fly to space, cars that zoom down the street, and boats that sail across the ocean. Just like your marshmallow propeller, these machines use different forces to move forward. Rockets use powerful engines that blast out hot gases, cars use engines that burn fuel, and boats use propellers that push water.

Propulsion and this project rely on Newton’s third law of motion: that every action has an equal and opposite reaction. Be sure to identify the action and equal and opposite reaction that occurs as you launch your marshmallows!

So next time you’re launching marshmallows with your cannon, remember the amazing force of propulsion. It’s what makes the marshmallows fly, rockets blast into space, and boats sail through the water. And who knows? Maybe one day you’ll use propulsion to create a super cool invention of your own!

Ready to make this project at home or in your classroom? Watch the video for an overview, gather the materials listed at the right, and follow the instructions below!

Required Materials

  • 1 balloon
  • 1 cardboard tube
  • tape
  • scissors
  • string

Step-By-Step Instructions

Step 1

Tie a knot at the opening of the balloon.

Step 2

Cut the balloon in half below the knot (where the circular part of the balloon starts).

Step 3

Stretch the balloon over the tube (we used a toilet paper roll) so the knot sits in the middle of the tube opening.

Step 4

Secure the balloon tightly with tape.

Step 5

Load your newly-constructed propeller with items to propel. We chose marshmallows, but you could use confetti, etc. Note: you’ll need to adjust how many of the items you load as each item’s weight and size will impact propulsion.

Step 6

Pull the knot as far back as you can without pulling the balloon off of the tube and launch