Michael hands Hannah a kendama, the Japanese cup-and-ball toy, and asks her to land a single catch. Then he brings out one built for him by Adam Savage of MythBusters and explains why a heavier kendama is a completely different physics problem. A kendama looks like a children's toy. It is really a pendulum, a lesson in angular momentum and a catching problem borrowed from spacecraft docking. Michael and Hannah get into why the swing timing barely changes when the ball gets heavier, why the trick is to match the ball's velocity rather than grab at it, why bending your knees on the catch is doing real work, and why the paint finish on a kendama changes how it plays. Then Hannah and Michael take on your questions: what would actually happen if you flew into Jupiter and kept going, whether there is a mathematical way to swim faster, and which books they'd hand an adult who wants to get back into maths after school ruined it. ------------------- For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit https://cancerresearchuk.org/restisscience Cancer Research UK is a registered charity in England and Wales (1089464), Scotland (SC041666), the Isle of Man (1103) and Jersey (247). A company limited by guarantee. Registered company in England and Wales (4325234) and the Isle of Man (5713F). Registered address: 2 Redman Place, London, E20 1JQ. ------------------- Video Editor: Jack Meek Animator: Sam Benson Video & Social: Bex Tyrrell Assistant Producer: Lucy Lipscombe Producer: Simona Rata Senior Producer: Lauren Armstrong-Carter Chief Digital Officer: Samuel Oakley Exec Producer: Neil Fearn