Physics: “Simple Waves” 1959 PSSC John Shive, Bell Laboratories; Physical Science Study Committee

Physical Science Study Committee Films (PSSC) playlist:

Physics & Physical Sciences playlist:

“John Shive [of Bell Laboratories] explains that pulse propagation on ropes and slinkies shows elementary characteristics of waves, such as different speeds in different media. He uses a torsion bar wave machine to repeat these experiments to demonstrate reflection and other phenomena.”

Public domain film, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

Wikipedia license:

In physics, a wave is an oscillation accompanied by a transfer of energy that travels through a medium (space or mass). Frequency refers to the addition of time. Wave motion transfers energy from one point to another, which displace particles of the transmission medium–that is, with little or no associated mass transport. Waves consist, instead, of oscillations or vibrations (of a physical quantity), around almost fixed locations.

A wave is a disturbance that transfers energy through matter or space There are two main types of waves. Mechanical waves propagate through a medium, and the substance of this medium is deformed. Restoring forces then reverse the deformation. For example, sound waves propagate via air molecules colliding with their neighbors. When the molecules collide, they also bounce away from each other (a restoring force). This keeps the molecules from continuing to travel in the direction of the wave.

The second main type, electromagnetic waves, do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields originally generated by charged particles, and can therefore travel through a vacuum. These types vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

Waves are described by a wave equation which sets out how the disturbance proceeds over time. The mathematical form of this equation varies depending on the type of wave. Further, the behavior of particles in quantum mechanics are described by waves. In addition, gravitational waves also travel through space, which are a result of a vibration or movement in gravitational fields.

A wave can be transverse, where a disturbance creates oscillations that are perpendicular to the propagation of energy transfer, or longitudinal: the oscillations are parallel to the direction of energy propagation. While mechanical waves can be both transverse and longitudinal, all electromagnetic waves are transverse in free space…

Slinky is a toy, a precompressed helical spring invented by Richard James in the early 1940s. 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, or appear to levitate for a period of time after it has been dropped. These interesting characteristics have contributed to its success as a toy in its home country of United States, resulting in many popular toys with slinky components in a wide range of countries…

Slinky was originally priced at $1, but many paid much more due to price increases of spring steel throughout the state of Pennsylvania, and has remained modestly priced throughout its history as a result of Betty James’ concern about the toy’s affordability for poor customers. Slinky has seen uses other than as a toy in the playroom: it has appeared in the classroom as a teaching tool, in wartime as a radio antenna, and in physics experiments with NASA. Slinky was inducted into the National Toy Hall of Fame at The Strong in Rochester, New York, in 2000. In 2002, Slinky became Pennsylvania’s official state toy, and, in 2003, was named to the Toy Industry Association’s “Century of Toys List.” In its first 60 years Slinky has sold 300 million units…