demonstrations:marshmallow_catapult

Marshmallow Catapult

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Energy, Simple Machines

Alternative titles: Exploring Potential and Kinetic Energy with a Catapult

Summary

Build a simple catapult using ice cream sticks, rubber bands, and a spoon to launch soft objects like marshmallows. This activity demonstrates how elastic potential energy can be converted into kinetic energy and how energy transfer creates motion.

Procedure

  • See links below for method.

Marshmallow Catapult - Lincolnwood Library:


How to make a Marshmallow Catapult - by Science Ireland - Declan Holmes:


📄 Marshmallow Catapult - Questacon: https://www.questacon.edu.au/learn-and-play/activities/marshmallow-catapult

📄 The Marshmallow Catapult Lab: https://cpennypacker82.weebly.com/uploads/5/9/2/4/59245729/marshmallowcatapultlab.pdf

Variations

  • Change the spoon size or stiffness to alter launch strength.
  • Adjust the number of base sticks to modify stability.
  • Try launching different lightweight objects (cotton balls, pom poms, or paper wads).
  • Build a larger catapult using wooden rulers or craft planks for comparison.

Safety Precautions

  • Always aim the catapult away from people, animals, or fragile objects.
  • Even small projectiles like marshmallows can cause injury if aimed at eyes or faces.
  • Use only soft, lightweight objects for launching.
  • Test in a clear area free from breakable items.

Questions to Consider

  • Why does the catapult fling objects so easily? (Elastic potential energy stored in bent materials is released as kinetic energy when the spoon springs back.)
  • What happens if you pull the spoon back farther? (More potential energy is stored, leading to greater launch speed—but too far can damage the catapult.)
  • Which parts of the catapult store the energy? (The rubber bands, spoon, and flexible sticks.)
  • Why does the marshmallow keep flying after release? (It has momentum and continues moving until forces like air resistance and gravity stop it.)
  • What is the difference between a catapult, ballista, and trebuchet? (All use stored energy, but the mechanisms for storing and releasing that energy differ.)