A pendulum to demonstrate Newton's law to preserve impulse and energy during an elastic impact of balls. A series of 5 identical steel balls in contact with each other, hanging on threads that can swing in only one common plane. When one of them is diverted and released, its impact on the other balls will cause only the last ball to bounce off the opposite side of the row. Its deviation will be almost identical to that of the the first one. Dimensions: 22 x 13 x 22 cm.One ball diameter: 2 cm.