What is inside of the ping pong ball?

Answer 1

Ping pong balls are made of celluloid, a lightweight, flexible plastic. An American inventor, John Wesley Hyatt, discovered this material in the late 1860s after he experimented with a mixture of cellulose nitrate and camphor. Although it is a tough, inexpensive product, celluloid is also extremely flammable because of unstable properties. Originally Hyatt wanted to use celluloid to replace the pricey ivory in billiard balls, but he discovered this fiery danger when billiard balls made with celluloid exploded upon colliding. Celluloid was later used for a variety of products, including combs, collars, Photography film, and toys, but it was slowly replaced by newer synthetic polymers. Today, celluloid is mainly used in the manufacture of ping pong balls, and because it is much lighter than other materials and has great tensile strength (causing the surface to remain stiff upon impact), it allows the balls to soar upon impact.