Memory Spring! Some special alloys of brass can be made to have a shape memory triggered by temperature. These springs quickly change their length from 1 cm to 2.5cm when heated above 90 C (done here with hot water) and just as quickly shrink back to original size when cooled (immersed in cold water). Useful in many applications, especially things like automatic fire sprinkler valves. This amazing property is probably due to a solid state phase transition similar to that of Nitinol wire called a martensitic transformation. ➡️ Repost from @physicsfun. Follow the link in their profile for information on where to buy this and many other physics toys. . . . . . #STEM #memorywire #physics #physicstoy #phasetransition #martensitic #memoryalloy #nitinol #alloy #thermodynamics #statisticalmechanics #thermostat #science #scienceisawesome