THE MARSHMALLOW CANNON

Published: May-2026 | Category: Fun With Science

How does pulling back a catapult further affect how fast and how far a marshmallow travels?

In this fun, hands-on physics experiment, students investigate how elastic potential energy is transferred into kinetic energy using a simple marshmallow cannon. By changing the pull-back angle and measuring both launch velocity and distance, learners can clearly see how stored energy affects projectile motion.

Using a Data Harvest Light Gate with EasySense software, this practical turns a classroom catapult activity into a measurable science investigation, helping students collect accurate real-time data rather than relying on stopwatches or estimates.

Watch the Experiment

See the full setup, application and results of the marshmallow cannon practical in the video below.

Learning Objectives

By the end of this activity, students will be able to:

• Explain how elastic potential energy is stored in stretched elastic bands
• Describe how stored energy is transferred into kinetic energy
• Measure launch velocity using a Light Gate
• Investigate how pull-back angle affects projectile distance
• Identify variables in a practical physics investigation
• Interpret results linked to energy transfer and projectile motion

Equipment Required

• Data Harvest Light Gate
• EasySense software
• Plastic or wooden spoon to act as the launch arm
• Elastic bands of similar size and strength
• Marshmallows
• Protractor
• Tape measure
• Clamp stand or heavy base
• Safety goggles

Experiment Setup

The marshmallow cannon is created using a spoon fixed to a base with elastic bands. When the spoon is pulled back, the elastic bands stretch and store elastic potential energy. When released, this stored energy is transferred to the spoon and marshmallow, launching the marshmallow forward.

The Light Gate is positioned so that the spoon or interrupt passes through the sensor at the moment of launch. This allows the launch velocity to be measured accurately using EasySense.

A tape measure is placed along the floor from the launch point so students can record the horizontal distance travelled by the marshmallow.

Method

1. Secure the marshmallow cannon firmly to the table using clamps or a heavy base.
2. Position the Light Gate so it detects the launch motion at the correct point.
3. Set up EasySense for timing and velocity measurement.
4. Place a tape measure on the floor from the launch position.
5. Pull the spoon back to a set angle, such as 20°.
6. Release the spoon and record the launch velocity from the Light Gate.
7. Measure the distance from the launch point to where the marshmallow first lands.
8. Repeat three times and calculate an average.
9. Repeat the investigation using different pull-back angles, such as 30°, 40° and 50°.

What’s Happening?

When the spoon is pulled back, the elastic bands stretch. This stores elastic potential energy. When the spoon is released, the stored energy is transferred into kinetic energy, causing the marshmallow to move.

The greater the pull-back angle, the more the elastic bands are stretched. This usually means more energy is stored and transferred, resulting in a higher launch velocity.

A higher launch velocity generally allows the marshmallow to travel further horizontally, although the relationship is not always perfectly linear because air resistance has a noticeable effect on light objects like marshmallows.

Results & Observations

Students should observe that:

• Increasing the pull-back angle increases the stretch in the elastic bands
• A greater stretch usually produces a higher launch velocity
• A higher launch velocity generally increases the distance travelled
• Marshmallows are strongly affected by air resistance because they are light and have a relatively large surface area
• Repeated trials help improve reliability and reduce the effect of unusual results

Why Use a Light Gate?

A Light Gate provides a more accurate way to measure speed than a stopwatch because it records the moment an object interrupts the beam. This reduces human reaction time errors and allows students to capture fast launch events more reliably.

This makes the practical ideal for introducing students to accurate timing, data logging and real-time measurement in physics investigations.

Questions to Explore

• What type of energy is stored in the elastic bands before release?
• What is the independent variable in this experiment?
• How does launch velocity change as pull-back angle increases?
• If velocity doubles, does the distance also double?
• Why does air resistance affect a marshmallow more than a heavier object of the same size?
• How could the experiment be improved to make the results more reliable?

Real-World Connections

This experiment links directly to projectile motion, energy transfer and forces. The same principles can be seen in sports, engineering, launching systems and any situation where stored energy is released to move an object.

By using simple classroom materials alongside accurate data logging equipment, students can connect everyday observations with measurable scientific evidence.

Conclusion

The marshmallow cannon experiment is a fun and memorable way to explore energy transfer and projectile motion. By adjusting the pull-back angle and measuring both launch velocity and distance, students can clearly see how stored elastic potential energy affects motion.

With a Data Harvest Light Gate and EasySense software, the practical becomes a more accurate and engaging investigation, giving students real data they can analyse, compare and explain.

Explore more:

• Data Harvest
• Data Harvest Store
• Wireless Bluetooth Sensors
• EasySense App