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physics

Recycling

Recycling is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Recycling rather than just read about it. In short: Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials.

Recycling — main illustration
Recycling — illustration

Key takeaways

  • Recycling belongs to physics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Recycling to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Recycling from memory before moving on to harder problems.

Reference excerpt

Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials. The recyclability of a material depends on its ability to reacquire the properties it had in its original state. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. It can also prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, reducing energy use, air pollution (from incineration) and water pollution (from landfilling). Recycling is a key component of modern waste reduction and represents the third step in the "Reduce, Reuse, and Recycle" waste hierarchy, contributing to environmental sustainability and resource conservation. It promotes environmental sustainability by removing raw material input and redirecting waste output in the economic system. There are some ISO standards related to recycling, such as ISO 15270:2008 for plastics waste and ISO 14001:2015 for environmental management control of recycling practice. Recyclable materials include many kinds of glass, paper, cardboard, metal, plastic, tires, textiles, batteries, and electronics. The composting and other reuse of biodegradable waste—such as food and garden waste—is also a form of recycling. Materials for recycling are either delivered to a household recycling center or picked up from curbside bins, then sorted, cleaned, and reprocessed into new materials for manufacturing new products. In ideal implementations, recycling a material produces a fresh supply of the same material—for example, used office paper would be converted into new office paper, and used polystyrene foam into new polystyrene. Some types of materials, such as metal cans, can be remanufactured repeatedly without losing their purity. With other materials, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so "recycling" of many products and materials involves their reuse in producing different materials (for example, paperboard). Another form of recycling is the salvage of constituent materials from complex products, due to either their intrinsic value (such as lead from car batteries and gold from printed circuit boards), or their hazardous nature (e.g. removal and reuse of mercury from thermometers and thermostats).

History During periods when resources were scarce, archaeological studies of ancient waste dumps show less household waste (such as ash, broken tools, and pottery), implying that more waste was recycled in place of new material. However, archaeological artefacts made from recyclable material, such as glass or metal, may neither be the original object nor resemble it, with the consequence that a successful ancient recycling economy can become invisible when recycling is synonymous with re-melting rather than reuse.

In pre-industrial times, there is evidence of scrap bronze and other metals being collected in Europe and melted down for continuous reuse. Paper recycling was first recorded in 1031 when Japanese shops sold repulped paper. In Britain dust and ash from wood and coal fires was collected by "dustmen" and downcycled as a base material for brick making. These forms of recycling were driven by the economic advantage of obtaining recycled materials instead of virgin material, and the need for waste removal in ever-more-densely populated areas. In 1813, Benjamin Law developed the process of turning rags into "shoddy" and "mungo" wool in Batley, Yorkshire, which combined recycled fibers with virgin wool. The West Yorkshire shoddy industry in towns such as Batley and Dewsbury lasted from the early 19th century to at least 1914. Industrialization spurred demand for affordable materials. In addition to rags, ferrous scrap metals were coveted as they were cheaper to acquire than virgin ore. Railroads purchased and sold scrap metal in the 19th century, and the growing steel and automobile industries purchased scrap in the early 20th century. Many secondary goods were collected, processed and sold by peddlers who scoured dumps and city streets for discarded machinery, pots, pans, and other sources of metal. By World War I, thousands of such peddlers roamed the streets of American cities, taking advantage of market forces to recycle post-consumer materials into industrial production. Manufacturers of beverage bottles, including Schweppes, began offering refundable recycling deposits in Great Britain and Ireland around 1800. An official recycling system with refundable deposits for bottles was established in Sweden in 1884, and for aluminum beverage cans in 1982; it led to recycling rates of 84–99%, depending on type (glass bottles can be refilled around 20 times).

Wartime

New chemical industries created in the late 19th century both invented new materials (e.g. Bakelite in 1907) and promised to transform valueless into valuable materials. Proverbially, you could not make a silk purse of a sow's ear—until the US firm Arthur D. Little published in 1921 "On the Making of Silk Purses from Sows' Ears", its research proving that when "chemistry puts on overalls and gets down to business [...] new values appear. New and better paths are opened to reach the goals desired." Recycling—or "salvage", as it was then usually known—was a major issue for governments during World War II, where financial constraints and significant material shortages made it necessary to reuse goods and recycle materials. These resource shortages caused by the world wars, and other such world-changing events, greatly encouraged recycling. It became necessary for most homes to recycle their waste, allowing people to make the most of what was available. Recycling household materials also meant more resources were left available for war efforts. Massive government campaigns, such as the National Salvage Campaign in Britain and the Salvage for Victory campaign in the United States, occurred in every fighting nation, urging citizens to donate metal, paper, rags, and rubber as a patriotic duty.

… excerpt ends here. Continue reading the full article.

Illustrations

Recycling: The three chasing arrows of the universal recycling symbol
The three chasing arrows of the universal recycling symbol
Recycling: Municipal waste recycling rate (%), 2015
Municipal waste recycling rate (%), 2015
Recycling: Inside a British factory, a textile worker rakes newly-made 'shoddy' which was then combined with new wool to make new cloth
Inside a British factory, a textile worker rakes newly-made 'shoddy' which was then combined with new wool to make new cloth
Recycling: American poster from World War II
American poster from World War II
Recycling: British poster from World War II
British poster from World War II

Worked examples

Example 1 — a first encounter with Recycling

Start with the simplest possible case. Write down what Recycling claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Recycling before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Recycling ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Recycling

In research
Recycling appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Recycling in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Recycling is common in secondary-school and first-year university syllabi. It links to neighbouring topics Energy conversion, Recycling, Waste management concepts, so understanding it makes those chapters shorter.
In everyday life
Look for Recycling outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Recycling in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Recycling means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Recycling out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Recycling in simple terms?

Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials.

Why does Recycling matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Recycling?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Recycling.

Tags

  • Energy conversion
  • Recycling
  • Waste management concepts
  • Water conservation

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