Slinky — BrandWiki

Slinky

The Slinky is a helical spring toy invented and developed by American naval engineer Richard T. James in 1943 and successfully demonstrated at Gimbels department store in Philadelphia on November 27, 1945.[1]

It can perform a number of tricks, including travelling down a flight of steps end-over-end as it stretches and re-forms itself with the aid of gravity and its own momentum; and appearing to levitate for a period of time after it has been dropped. These interesting characteristics have contributed to its success in its home country of the United States, and it has inspired many popular toys with Slinky-like components, in a wide range of countries.

History

Creation

In 1943, Richard T. James, a naval mechanical engineer, observed a spring "stepping" downward after being knocked off a shelf, then coming to rest in a vertical position.[2] James's wife Betty later recalled, "He came home and said, 'I think if I got the right property of steel and the right tension, I could make it walk.'"

Physical properties

The physical laws that govern the mechanics of a Slinky are Hooke's law and gravitation.

Period of oscillation

The oscillation of a vertically suspended Slinky has the periodic duration[15]

where L is the length of the Slinky, and g the acceleration due to gravity, approximately. The expression for T is independent of the spring constant k and the mass m of the Slinky. For a spring pendulum one would expect such a dependence. This is because the dependence on k and m is hidden in the length L(k,m):

(W is the weight).

This allows one to write:

This expression differs from the ordinary spring pendulum

because for the spring pendulum one assumes a massless spring with a mass m attached at the bottom.

Operation

When set in motion on a stepped platform such as a stairway, the Slinky transfers energy along its length in a longitudinal wave. The whole spring descends end over end in a periodic motion as if it were "walking" down one step at a time.[16]

When the top end of the Slinky is dropped, the energy of the tension change must propagate to the bottom end before both sides begin to fall; the top of an extended Slinky will drop while the bottom initially remains in its original position, compressing the spring.[17] This creates a suspension time of ~0.3 s for an original Slinky,[18][19] but has potential to create a much larger suspension time. A suspended Slinky's center of mass is accelerating downward at 1g (about 32 ft/s2); when released, the lower portion moves up toward the top portion with an equivalent, constant upward acceleration as the tension is relieved. As the spring contracts, every point along its length will accelerate downward with gravity and tension, and undergo a decrease in overall downward acceleration related to height along the spring due to the spring force changing with extension; at the bottom of the spring the upward initial acceleration reduces in accordance with Hooke's Law as the spring contracts, but the center toward which it is moving gets closer. Thus the base will have been displaced sufficiently toward the center of inertial mass for it to appear to have hung still.

Commercial history

Jingle

The jingle for the Slinky television commercial was created in Columbia, South Carolina in 1962 with Johnny McCullough and Homer Fesperman writing the music and Charles Weagly penning the lyrics. It became the longest-running jingle in advertising history.[20]

The jingle has itself been parodied and referenced in popular culture. It is seen in the "Log" commercial on The Ren & Stimpy Show and sung by actor Jim Carrey in Ace Ventura: When Nature Calls. It is also referenced in the movie Lords of Dogtown, where it is sung in full by Emile Hirsch, and is sung by Eddie Murphy as part of the final routine in the stand-up comedy film Eddie Murphy Raw. It was also parodied in an ad for the Isuzu Amigo used as a promo for the vehicle's return in late March 1998, nearly two months before the ad was pulled due to criticism from the company that made the Slinky.[21]

Slinky Dog

Early in the history of James Industries, Helen Herrick Malsed of Washington state sent the company a letter and drawings for developing Slinky pull-toys. The company liked her ideas, and Slinky Dog and Slinky Train were added to the company's product line. Slinky Dog, a small plastic dog whose front and rear ends were joined by a metal Slinky, debuted in 1952. Malsed received royalties of $60,000 to $70,000 annually for 17 years on her patent for the Slinky pull-toy idea, but never visited the plant.[22]

In 1995, the Slinky Dog was redesigned for all of Pixar's Toy Story films, voiced by Jim Varney and Blake Clark. James Industries had discontinued their Slinky Dog a few years previously. Betty James approved of the new Slinky Dog, telling the press, "The earlier Slinky Dog wasn't nearly as cute as this one."[23]

Plastic Slinky

Plastic Slinkys are also available. They can be made in different colors. Many of them are made with the colors of the rainbow in rainbow order. They were marketed in the 1970s as a safer alternative to metal Slinkys as they did not present a hazard when inserted into electrical sockets. The plastic spring toy, known as the Plastic Slinky, was invented by Donald James Reum of Avon Plastics in Albany, Minnesota. Reum came up with the idea as he was experimenting with different techniques to produce a spiral hose for watering plants. However, as it came off the assembly line, according to his children, it looked more like a "Slinky". He worked at it until it came out perfectly and then went to Betty James with his prototype. Reum manufactured the Plastic Slinky for Betty James for several years. Eventually Betty James decided to manufacture the product exclusively through James manufacturing, effectively ending the production of the toy by the small Minnesota company. Reum's patent number, 4120929 was filed on December 28, 1976, and issued by the U.S. Patent Office on October 17, 1978.[24]