Slinky

The Slinky is a helical spring toy that captures the imagination through unique motion.

It is famous for its ability to travel down stairs end-over-end. This movement occurs as the spring stretches and re-forms itself using gravity and momentum. When dropped, a Slinky can even appear to levitate for a short time. This phenomenon happens because the energy of the tension change must travel to the bottom. The top drops while the bottom stays still for approximately 0.3 seconds. These physical properties have made the Slinky a massive success in the United States.

The mechanics of a Slinky are governed by gravitation and Hooke's law. Hooke's law describes how a spring responds to being stretched or compressed. When placed on a staircase, the Slinky transfers energy along its length in a longitudinal wave. This wave allows the spring to descend in a periodic motion. This motion makes the toy look as if it is walking down one step at a time. The center of mass accelerates downward at 1g, which is about 9.8 meters per second squared. As the spring contracts, the tension is relieved and the bottom moves toward the top.

There are different types of Slinkys available for people to enjoy. The original version was made of high-grade blue-black Swedish steel. These early models were tall and contained 98 coils of wire. Later, a plastic version was introduced to provide a safer alternative.

Plastic Slinkys often feature bright rainbow colors. Donald James Reum invented the plastic version while experimenting with spiral hoses for plants. He eventually brought his prototype to Betty James. The company later decided to manufacture these plastic versions exclusively.

The history of the Slinky began in 1943 with Richard T. James. He was a naval mechanical engineer who observed a spring "stepping" downward after falling off a shelf. James spent a year experimenting with different steel wires to find the right tension. He wanted to create a spring that could truly walk. His wife, Betty, was initially skeptical but became a believer once the toy was fine-tuned. They formed James Industries in Clifton Heights, Pennsylvania, to manufacture the toy. The Slinky was successfully demonstrated at Gimbels department store in Philadelphia on November 27, 1945.

Commercial success for the Slinky arrived very quickly. During the Gimbels demonstration, the first 400 units sold in just 90 minutes. The original price was only $1 per unit. Betty James later took over the company in 1960 after Richard left to become a missionary in Bolivia. She moved the company to Hollidaysburg, Pennsylvania, in 1964. Betty worked hard to keep the toy affordable for less affluent customers. In its first 60 years of production, approximately 300 million Slinkys were sold worldwide.

Beyond simple play, the Slinky has served many surprising roles. It has been used as a classroom teaching tool to explain physics. During the Vietnam War, soldiers used it as a portable, extendable radio antenna. It resonated between 7 and 8 MHz, which helped with local HF communication. In 1985, astronauts on the Space Shuttle Discovery used the toy to demonstrate weightlessness. They created a video showing how the Slinky appears to "droop" in space. People have even used them to make music with an instrument called a Helixophone.

The Slinky's influence extends into many parts of modern culture. The famous television jingle was created in 1962 in South Carolina. It became the longest-running jingle in the history of advertising. The toy has also inspired other products, such as the Slinky Dog. This pull-toy was inspired by drawings sent by Helen Herrick Malsed. The Slinky was inducted into the National Toy Hall of Fame in 2000. It was also named to the Toy Industry Association's Century of Toys List in 2003.