======Surface Tension Boat====== **Materials: **{{$demo.materials_description}}\\ **Difficulty: **{{$demo.difficulty_description}}\\ **Safety: **{{$demo.safety_description}}\\ \\ **Categories:** {{$demo.categories}} \\ **Alternative titles:** Soap-Powered Model Boa ====Summary==== {{$demo.summary}} ====Procedure==== -Cut a small boat (~5 cm long) from a foam tray or non-corrugated cardboard with a narrow notch at the back. -Fill a shallow tray or pie tin with water. -Place the boat onto the water. -Pour a small amount of dish soap into the notch and watch the boat accelerate forward for a few seconds. -Rinse the tray and boat thoroughly with fresh water to remove soap before repeating. ====Links==== Soap Powered Boat Experiment! - Boundles Brilliance: {{youtube>udxCQ7S3zlU?}}\\ Exploring the Physics of a Soap-Powered Boat - JaDropping Science {{youtube>3DRnthZRjqA?}}\\ 📄 Build A Soap Powered Model Boat - Science Bob: [[https://sciencebob.com/build-a-soap-powered-model-boat/]]\\ 📄 Soap-Powered Boats - Science World: [[https://www.scienceworld.ca/resource/soap-powered-boats/]]\\ ====Variations==== *Compare different soaps (dish, hand soap, shampoo) to see which produces the longest run. *Test water temperature (cold vs. warm) and note effects on speed and distance. *Try different hull materials (foam, thin plastic, card) and shapes or notch sizes to optimize performance. *Load the boat with a tiny paper clip to test how added mass affects distance. *Apply soap asymmetrically (only one notch edge) and observe any turning. ====Safety Precautions==== *Do not taste the water or soap; wash hands after the activity. *Wipe up spills promptly to prevent slipping. ====Questions to Consider==== *Why does the boat move only when fresh soap is added? What happens once the water surface is contaminated with soap? *How does reducing surface tension behind the boat create a net forward force? *Which design or material gave the best distance, and why? *How do temperature and added mass change the outcome?