The ups and downs of a yo-yo are based on physics but will it work without gravity? If you woke up today pondering this question, here's a live demonstration for you.
First, the physics: A yo-yo mainly relies on the laws of conservation of angular momentum to perform tricks. The basic up-and-down motion is caused by the string unwinding from the central axle, which causes the yo-yo body to spin rapidly.
When it reaches the end of the string, the angular momentum of the body gives it the energy to wind the string up again, bringing the yo-yo back.
Perhaps surprisingly, this works just as well in microgravity, providing you keep the string taut. In 2012, NASA astronaut Don Pettit took a yo-yo on board the International Space Station and demonstrated several tricks, including some he invented that actually require weightlessness.