======Liquid Nitrogen Hovercraft====== **Materials: **{{$demo.materials_description}}\\ **Difficulty: **{{$demo.difficulty_description}}\\ **Safety: **{{$demo.safety_description}}\\ \\ **Categories:** {{$demo.categories}} \\ **Alternative titles:** ====Summary==== {{$demo.summary}} ====Procedure==== - Break chalk into small pieces. - Place the chalk pieces into a container of liquid nitrogen until thoroughly cooled. - Using insulated gloves and tongs, remove a piece of frozen chalk. - Immediately set the chalk onto a smooth, hard surface such as hardwood or linoleum flooring. - Observe as the chalk glides and hovers on a thin cushion of rapidly escaping nitrogen gas. - Repeat with additional pieces to show consistency of the effect. ====Links==== Hovercraft chalk - J Rhee: {{youtube>mhe3n--Q_W8?}}\\ 📄 Things to Do with Liquid Nitrogen (activity 4.) - Thought Co: [[https://www.thoughtco.com/liquid-nitrogen-activities-and-projects-603678]]\\ ====Variations==== * Try different materials (erasers, coins, or small stones) to compare how they behave after immersion in liquid nitrogen. * Place the chalk on slightly inclined surfaces to make it “drive” in one direction. ====Safety Precautions==== * Safety glasses required. * Wear cryogenic gloves when handling liquid nitrogen. * Use tongs to remove chalk from liquid nitrogen. * Only perform on sturdy, non-fragile surfaces that won’t crack from the cold. * Avoid touching frozen chalk directly, as it may cause frostbite. * Ensure good ventilation to avoid nitrogen buildup. ====Questions to Consider==== * Why does the chalk glide instead of sticking to the floor? * What role does the escaping nitrogen gas play in this demonstration? * How is this effect similar to a hovercraft or an air hockey table? * Would the effect be stronger or weaker on a rough surface compared to a smooth one? * What does this tell us about friction and lubrication?