Physics Toy

I came across this toy and totally thought of the wonderful world of Physics! When you push down one of the dolphins and then let go, the dolphins on each side move towards the ball in a circular path alternatively. First of all, because of the low friction between the metal parts, the dolphins will continue to move for quite some time after one of the dolphins was first pushed down. This exhibits Newton's first law of motion because the dolphins continue to move until the force of friction eventually acts on the system. This dolphin toy also shows the idea of conservation of total mechanical energy. When one pair of dolphins is pulled up a certain distance and held at rest, the kinetic energy is 0 and the potential energy is mgh. The total mechanical energy of the pair of dolphins just before they change direction is the same as the total mechanical energy in the beginning, except in the end the potential energy is 0 and the kinetic energy is mgh. The forces acting on the system include a magnetic force from a magnet inside the blue base (pulling the dolphin downwards), gravity (which is always, always, always pulling down towards the center of the earth, and tension.