Newton's cradle
Eventually the last ball, having received a successively diminished portion of the first's energy and momentum, begins the process anew in the opposite direction.
)[citation needed] In each phase of the process, efficient mechanical energy is lost; Newton's cradle is not a perpetual motion machine.
Newton's cradle can be modeled fairly accurately with simple mathematical equations with the assumption that the balls always collide in pairs.
All the animations in this article show idealized action (simple solution) that only occurs if the balls are not touching initially and only collide in pairs.
For the case of two balls constrained to a straight path by the strings in the cradle, the velocities are a single number instead of a 3D vector for 3D space, so the math requires only two equations to solve for two unknowns.
The effect can also be seen when a sharp and strong pressure wave strikes a dense homogeneous material immersed in a less-dense medium.
It applies to all perfectly elastic identical balls that have no energy losses due to friction and can be approximated by materials such as steel, glass, plastic, and rubber.
For two balls colliding, only the two equations for conservation of momentum and energy are needed to solve the two unknown resulting velocities.
For example, five balls have four colliding points and scaling (dividing) three of them by the fourth gives the three extra variables needed to solve for all five post-collision velocities.
Newtonian, Lagrangian, Hamiltonian, and stationary action are the different ways of mathematically expressing classical mechanics.
This is due to the pendulum phenomenon of different small angle disturbances having approximately the same time to return to the center.
This shows that in the common case of steel balls, unnoticed separations can be important and must be included in the Hertzian differential equations, or the simple solution gives a more accurate result.
This is fast enough for the Hertzian solution to not require a substantial modification to adjust for the delay in force propagation through the balls.
In less-rigid but still very elastic balls such as rubber, the propagation speed is slower, but the duration of collisions is longer, so the Hertzian solution still applies.
Making the contact surfaces flatter can overcome this to an extent by distributing the compression to a larger amount of material but it can introduce an alignment problem.
[9] Newton acknowledged Mariotte's work, along with Wren, Wallis and Huygens as the pioneers of experiments on the collisions of pendulum balls, in his Principia.
[citation needed] However, in early 1967, an English actor, Simon Prebble, coined the name "Newton's cradle" (now used generically) for the wooden version manufactured by his company, Scientific Demonstrations Ltd.[10] After some initial resistance from retailers, they were first sold by Harrods of London, thus creating the start of an enduring market for executive toys.
[citation needed] Later a very successful chrome design for the Carnaby Street store Gear was created by the sculptor and future film director Richard Loncraine.
A smaller-scale version constructed by them consists of five 15-centimetre (6 in) chrome steel ball bearings, each weighing 15 kilograms (33 lb), and is nearly as efficient as a desktop model.
The cradle device with the largest-diameter collision balls on public display was visible for more than a year in Milwaukee, Wisconsin, at the retail store American Science and Surplus (see photo).
[citation needed] Newton's cradle appears in some films, often as a trope on the desk of a lead villain such as Paul Newman's role in The Hudsucker Proxy, Magneto in X-Men, and the Kryptonians in Superman II.
It was featured more prominently as a series of clay pots in Rosencrantz and Guildenstern Are Dead, and as a row of 1968 Eero Aarnio bubble chairs with scantily clad women in them in Gamer.
champion Ken Jennings and musician John Roderick, focused on the history of Newton's cradle.
[14] Newton's cradle is also featured on the desk of Deputy White House Communications Director Sam Seaborn in The West Wing.
In the Futurama episode "The Day the Earth Stood Stupid", professor Hubert Farnsworth is shown with his head in a Newton's cradle and saying he's a genius as Philip J. Fry walks by.
Progressive rock band Dream Theater uses the cradle as imagery in album art of their 2005 release Octavarium.
Rock band Jefferson Airplane used the cradle on the 1968 album Crown of Creation as a rhythm device to create polyrhythms on an instrumental track.
