modern metal yoyo with ball bearing works totally different with the old. it can spin about 5mins within one throw for some reason. and can it spin about 1min if I throw it horizontally? you may wonder about what is a horizontal throw. then see the video post below. https://vimeo.com/39247415 To my disappointment, a yoyo that can spin more than 5mins vertically cannot even spin for 5 seconds horizontally? What leads the depressing result? Can someone give me a force analysis? I guess the tension and gravity is the key while it spin horizontally. I think the yoyo spinning horizontally just like a spintop while flying around the air. And it do precession once we throw it because of the unbalance. So the way to keep longer spin time during horizontal condition is to reduce the precession speed. According to the w(precession)=mgr/Iw m -------mass r -------- distance between original center of rotation and the center of mass I ---------- moment of inertia w ----------- the rotation speed of object L=Iw means with a given throw the Iw is constant. So the only way we can do is to decrease the yoyo’s mass and shorten the string?