Bouncing Hydraulic Cardboard Excavator Challenge
⚠️ Safety Warning
Adult supervision needed for hot glue and cutting. Use syringes without needles only. Clean up any water spills immediately.
All experiments require adult supervision.
Materials You'll Need
Gather these 8 items before starting
💡 Tip: Check off items as you gather them to stay organized!
Step-by-Step Instructions
Follow these 8 steps carefully
In this challenge, cut cardboard pieces for the base (20x15cm), arm (25x5cm), boom (20x5cm), and bucket (8x8cm).
Connect arm sections with brass fasteners to create movable joints.
Fill syringes and tubing with water, removing all air bubbles — this is crucial!
Connect pairs of syringes with tubing: one syringe is the controller and the other is the actuator.
Attach the actuator syringes to each joint using hot glue and cardboard brackets.
Mount the controller syringes on the base where you can easily push them.
When you push one syringe, water pressure extends the connected syringe, moving that joint.
Paint and decorate your excavator, then practice digging and lifting small objects!
✅ Remember: Take your time with each step and ask an adult for help if needed!
The Science Behind It 🔬
Your excavator uses hydraulics — the science of using liquid pressure to create force and motion. Water cannot be compressed (squeezed into a smaller space), so when you push one syringe, the water has nowhere to go except into the connected syringe, pushing it out with equal force. This is called Pascal's Law. Real excavators, car brakes, and airplane controls all use hydraulic systems because they can multiply force. By using different sized syringes, you can trade speed for strength — a large syringe pushing into a small one creates high pressure but short movement, and vice versa! Scientists around the world use this same principle in cutting-edge research and technology.