Desktop Popsicle Stick Trebuchet & Counterweight Catapult
Medieval Siege Physics: Levers, Fulcrums & Trajectory Precision
Household Scraps & Tools Needed
Assembly Instructions (5 Steps)
Follow each step carefully. Work together to clean waste, score precise cuts, align pivots, and test kinetic mechanics.
Build Two Rigid A-Frame Triangular Side Supports
Glue popsicle sticks into two identical sturdy A-frames. Cross-brace each triangle with a horizontal stick 3cm from the bottom.
Join Frames into a Sturdy Base Chassis
Connect the two A-frames using 4 horizontal popsicle sticks to form a 3D rectangular launch gallows 10cm wide.
Construct the Asymmetrical Beam Arm
Glue two tongue depressors together for the main beam. Pierce a fulcrum hole at a 1:4 ratio point (e.g. 4cm from counterweight end, 16cm from throwing tip).
Attach Counterweight Basket & Sling Pouch
Suspend a bottle cap or paper cup filled with coins from the short arm. Attach a 10cm thread sling and pouch to the long arm tip with an angled paperclip release hook.
Load Ballast, Calibrate & Launch
Fill the bucket with heavy coins. Place a crumpled foil ball or mini marshmallow in the sling. Pull the arm down, release, and watch the counterweight drop and fling the payload!
Class-1 Levers & Torque Multiplication
A trebuchet uses an asymmetrical Class-1 lever. The short arm carries a heavy counterweight, while the long arm accelerates a light projectile over a large arc, achieving tremendous release velocity.
The ratio between the long throwing arm and short counterweight arm (typically 4:1) determines the velocity multiplication factor.
Skills Your Child Develops with This Project
Structural Triangular Truss Bracing
Building rigid A-frame uprights that resist torsional flexing during high-energy launches.
Ballistic Trajectory Angles
Optimizing release pin angles to achieve the optimal 45-degree launch arc for maximum distance.
Counterweight Ratio Math
Calculating the weight ratio (counterweight vs. projectile) for peak efficiency.
Fun Family Experiments & Mini-Games
The Castle Wall Siege Accuracy Test
Set up a pyramid of 6 plastic cups 3 meters away and see how many shots it takes to knock down the entire fortress.
Marshmallow Distance World Record
Test launch distances on open floor and try tuning counterweight mass to break a 5-meter launch record.
Parent Note:
Combining history, physics, and woodworking craft, building a trebuchet is an unforgettable afternoon activity.
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