Toy physics

Super balls are a well-known toy made from an elastic polymer so that they have very high coefficients of restitution (around 0.9) meaning that they bounce back from a surface with 90% of their initial velocity. Wham-O, the manufacturers of the original super ball, produced a giant version of the toy as a promotional stunt. The ball was accidentally dropped from a room on the 23rd floor of a hotel in Australia. It is said to have bounced back up to the 15th floor on its first bounce and then struck a parked car, causing considerable damage.

 Silly Putty® was first created in 1943 by James Wright, an engineer at General Electric, who mixed silicone oil with boric acid. It is reported that Wright threw the resulting goo onto the floor and was surprised to observe that it bounced. The engineers at General Electric failed to develop a use for the strange new material and it was six years before the material was marketed as a toy. ‘The Great Silly Putty Drop’ experiment was carried out at Alfred University in 1989. Some curious researchers wanted to determine whether a 45 kg ball of the putty, dropped from the top of the engineering building, would bounce or shatter. To the surprise of many, the ball initially bounced up to a height of 2.4 m and then shattered when it returned to the ground. The strange properties of Silly Putty are thought to arise from weak intermolecular oxygen-boron bonds, which are continually being made and broken.

Silly Putty is described as having time-dependent properties: if it is pulled apart slowly it forms long strands, but a sudden blow from a hammer can cause it to shatter. These properties resemble those of polymers, which can transition into a brittle state.