New! Sign up for our free email newsletter.
Reference Terms
from Wikipedia, the free encyclopedia

Newton's cradle

Newton's cradle or Newton's balls, named after Sir Isaac Newton is a device that demonstrates conservation of momentum and energy.

It is constructed from a series of pendulums (usually five in number) abutting one another. Each pendulum is attached to a frame by two strings of equal length angled away from each other. If these strings are not same in length, the balls would then be unbalanced. This string arrangement restricts the pendulums' movements to the same plane.

The behaviour of the pendulum follows from the conservation of momentum and kinetic energy only in the case of two pendula. Indeed, if there are r pendula there are also r unknown velocities to be calculated from the initial conditions. An additional condition for the observed outcome is that a shock wave has to propagate dispersion free through the chain.

The principle demonstrated by the device, the law of impacts between bodies, was first demonstrated by the French physicist, Abbé Mariotte in the 17th century. Sir Isaac Newton acknowledged Mariotte's work, among that of others, in hisPrincipia.

In pedagogic settings, a cradle device is sometimes used to present the concept of "action-reaction" (Newton's third law), with the words said to the cadence of the clacking pendulums as they execute a single cycle of swinging and clacking oscillation. This is not a very clear presentation of action-reaction. In fact, the conservation laws can be easily derived from Newton's second and third laws.

Related Stories
 


Matter & Energy News

August 17, 2025

Researchers have unveiled a new quantum material that could make quantum computers much more stable by using magnetism to protect delicate qubits from environmental disturbances. Unlike traditional approaches that rely on rare spin-orbit ...
Rice University scientists have discovered a way to make tiny vibrations, called phonons, interfere with each other more strongly than ever before. Using a special sandwich of silver, graphene, and silicon carbide, they created a record-breaking ...
Researchers have found a clever way to make quantum dots, tiny light-emitting crystals, produce streams of perfectly controlled photons without relying on expensive, complex electronics. By using a precise sequence of laser pulses, the team can ...
Scientists have developed a lightning-fast AI tool called HEAT-ML that can spot hidden “safe zones” inside a fusion reactor where parts are protected from blistering plasma heat. Finding these areas, known as magnetic shadows, is key to keeping ...
Scientists have found that microscopic gold clusters can act like the world’s most accurate quantum systems, while being far easier to scale up. With tunable spin properties and mass production potential, they could transform quantum computing and ...
A team of engineers at RMIT University has developed a groundbreaking 3D-printed titanium alloy that s stronger, more ductile, and nearly 30% cheaper to produce than the traditional standard. By replacing expensive vanadium with more accessible ...
AI is helping scientists crack the code on next-gen batteries that could replace lithium-ion tech. By discovering novel porous materials, researchers may have paved the way for more powerful and sustainable energy storage using abundant elements ...
A Penn State-led research team has unraveled the long-standing mystery of how lightning begins inside thunderclouds. Their findings offer the first quantitative, physics-based explanation for lightning initiation—and a glimpse into the stormy ...
Scientists have cracked open a mysterious layer inside batteries, using cutting-edge 3D atomic force microscopy to capture the dynamic molecular structures at their solid-liquid interfaces. These once-invisible electrical double layers (EDLs) twist, ...
Deep beneath the Swiss-French border, the Large Hadron Collider unleashes staggering amounts of energy and radiation—enough to fry most electronics. Enter a team of Columbia engineers, who built ultra-rugged, radiation-resistant chips that now ...
Researchers are exploring AI-powered digital twins as a game-changing tool to accelerate the clean energy transition. These digital models simulate and optimize real-world energy systems like wind, solar, geothermal, hydro, and biomass. But while ...
Deep in Serbia's Jadar Valley, scientists discovered a mineral with an uncanny resemblance to Superman's Kryptonite both in composition and name. Dubbed jadarite, this dull white crystal lacks the ...

Latest Headlines

updated 12:56 pm ET