A competition for operating the “world’s largest yo-yo” was won on Wednesday by Eyal Moshe Cohen, a mechanical engineering student at the Technion-Israel Institute of Technology.Yishai Zimmerman, 78, and his 16-year-old granddaughter Golan won second prize, while a student group called Kiss took third place at the Techno- Rosh competition held during the school’s board of governors meetings.Cohen released his yo-yo from a 30-meter-tall crane.The rules required that after it was dropped that it rise by at least 20 meters to qualify.Then it had to descend and rise again as many times as possible.The prizes were NIS 10,000, NIS 5,000 and NIS 3,000.Cohen served as an officer in the paratroopers and was accepted to the Technion after doing preparatory courses. He built his yo-yo by engraving it on a circular piece that functioned like a car’s flywheel.The momentum was thus preserved so it could climb back many times.“Every time I lowered it I added weight until I discovered the ideal weight. I am glad that it worked,” Cohen said.His mother, Gilah, said that her son had taken apart every electric device in the house from a young age. She was glad when he also learned to assemble the parts.Techno-Rosh was launched in 2003 when Niv-Ya Dorban, an outstanding Technion student, was murdered by a thief on a quiet Tel Aviv street that year. The prizes are financed by Dr. Robert Shillman, who studied at the Technion.