Energy saving: due to the air resistance and friction, it will not last forever. Newtonian Law The ki-netic energy art ball can move continuously for 8-15 seconds, with excellent torque and center of mass. It not only shows the movement of the pendulum, but also helps to show the law of conservation of impulse and conservation of energy. -Ki-magnetic art: it is a fun way to learn science, perfect for children to experience mechanical fun in classroom education or play with it, improves children's ability to explore scientific secrets. - Unique ornament: made of plastic, suitable for table sports decoration. Surprise your friends with this clever toy and enjoy the fun of science. - Stress Reliever: Suitable for adult decompression, it is great to relieve fatigue and stress after a hard working day, perfect for space science lessons or office decoration, a great teaching tool to explain eternal physics. Perfect for birthdays, holidays, Christmas and Father's Day gifts. -Optional: Yellow (USB version), Red (USB version), Wine Red (Battery version).