Nouns

 Nouns

Main article: English nouns

Many common suffixes form nouns from other nouns or from other types of words, such as -age (shrinkage), -hood (sisterhood), and so on,[3] though many nouns are base forms containing no such suffix (cat, grass, France). Nouns are also created by converting verbs and adjectives, as with the words talk and reading (a boring talk, the assigned reading).

Nouns are sometimes classified semantically (by their meanings) as proper and common nouns (Cyrus, China vs frog, milk) or as concrete and abstract nouns (book, laptop vs embarrassment, prejudice). A grammatical distinction is often made between count (countable) nouns such as clock and city, and non-count (uncountable) nouns such as milk and decor. Some nouns can function both as countable and as uncountable such as "wine" in This is a good wine.

Countable nouns generally have singular and plural forms. In most cases the plural is formed from the singular by adding -[e]s (as in dogs, bushes), although there are also irregular forms (woman/women, foot/feet), including cases where the two forms are identical (sheep, series). For more details see English plural. Certain nouns can be used with plural verbs even though they are singular in form, as in The government were ... (where the government is considered to refer to the people constituting the government). This is a form of synesis, and is more common in British than American English. See English plural § Singulars with collective meaning treated as plural.

English nouns are not marked for case as they are in some languages, but they have possessive forms, through the addition of -'s (as in John's, children's) or just an apostrophe (with no change in pronunciation) in the case of -[e]s plurals (the dogs' owners) and sometimes other words ending with -s (Jesus' love). More generally the ending can be applied to noun phrases (as in the man you saw yesterday's sister); see below. The possessive form can be used either as a determiner (Manyanda's cat) or as a noun phrase (Manyanda's is the one next to Jane's).

The classification of the possessive as an affix or a clitic is the subject of debate. It differs from the noun inflection of languages such as German, in that the genitive ending may attach to the last word of the phrase. To account for this, the possessive can be analysed, for instance as a clitic construction (an "enclitic postposition") or as an inflection of the last word of a phrase ("edge inflection").

Relative clauses

 Relative

Main article: English relative clauses

For "who/whom" and related forms, see Who (pronoun).

The main relative pronouns in English are who (with its derived forms whom and whose), which, and that.

The relative pronoun which refers to things rather than persons, as in the shirt, which used to be red, is faded. For persons, who is used (the man who saw me was tall). The oblique case form of who is whom, as in the man whom I saw was tall, although in informal registers who is commonly used in place of whom.

The possessive form of who is whose (for example, the man whose car is missing); however the use of whose is not restricted to persons (one can say an idea whose time has come).

The word that as a relative pronoun is normally found only in restrictive relative clauses (unlike which and who, which can be used in both restrictive and unrestrictive clauses). It can refer to either persons or things, and cannot follow a preposition. For example, one can say the song that [or which] I listened to yesterday, but the song to which [not to that] I listened yesterday. The relative pronoun that is usually pronounced with a reduced vowel (schwa), and hence differently from the demonstrative that (see Weak and strong forms in English). If that is not the subject of the relative clause, it can be omitted (the song I listened to yesterday).

The word what can be used to form a free relative clause – one that has no antecedent and that serves as a complete noun phrase in itself, as in I like what he likes. The words whatever and whichever can be used similarly, in the role of either pronouns (whatever he likes) or determiners (whatever book he likes). When referring to persons, who(ever) (and whom(ever)) can be used in a similar way.

"There"

The word there is used as a pronoun in some sentences, playing the role of a dummy subject, normally of an intransitive verb. The "logical subject" of the verb then appears as a complement after the verb.

This use of there occurs most commonly with forms of the verb be in existential clauses, to refer to the presence or existence of something. For example: There is a heaven; There are two cups on the table; There have been a lot of problems lately. It can also be used with other verbs: There exist two major variants; There occurred a very strange incident.

The dummy subject takes the number (singular or plural) of the logical subject (complement), hence it takes a plural verb if the complement is plural. In informal English, however, the contraction there's is often used for both singular and plural.

The dummy subject can undergo inversion, Is there a test today? and Never has there been a man such as this. It can also appear without a corresponding logical subject, in short sentences and question tags: There wasn't a discussion, was there? There was.

The word there in such sentences has sometimes been analyzed as an adverb, or as a dummy predicate, rather than as a pronoun. However, its identification as a pronoun is most consistent with its behavior in inverted sentences and question tags as described above.

Because the word there can also be a deictic adverb (meaning "at/to that place"), a sentence like There is a river could have either of two meanings: "a river exists" (with there as a pronoun), and "a river is in that place" (with there as an adverb). In speech, the adverbial there would be given stress, while the pronoun would not – in fact, the pronoun is often pronounced as a weak form, /ðə(r)/.

Reciprocal

The English reciprocal pronouns are each other and one another. No consistent distinction in meaning or use can be found between them. Like the reflexive pronouns, their use is limited to contexts where an antecedent precedes it. In the case of the reciprocals, they need to appear in the same clause as the antecedent.

Other

Other pronouns in English are often identical in form to determiners (especially quantifiers), such as many, a little, etc. Sometimes, the pronoun form is different, as with none (corresponding to the determiner no), nothing, everyone, somebody, etc. Many examples are listed as indefinite pronouns. Another indefinite (or impersonal) pronoun is one (with its reflexive form oneself and possessive one's), which is a more formal alternative to generic you.

Personal

 Personal

Main article: English personal pronouns

The personal pronouns of modern standard English are presented in the table above. They are I, you, she, he, it, we, and they. The personal pronouns are so-called not because they apply to persons (which other pronouns also do), but because they participate in the system of grammatical person (1st, 2nd, 3rd).

The second-person forms such as you are used with both singular and plural reference. In the Southern United States, y'all (you all) is used as a plural form, and various other phrases such as you guys are used in other places. An archaic set of second-person pronouns used for singular reference is thou, thee, thyself, thy, thine, which are still used in religious services and can be seen in older works, such as Shakespeare's—in such texts, the you set of pronouns are used for plural reference, or with singular reference as a formal V-form. You can also be used as an indefinite pronoun, referring to a person in general (see generic you), compared to the more formal alternative, one (reflexive oneself, possessive one's).

The third-person singular forms are differentiated according to the gender of the referent. For example, she is used to refer to a woman, sometimes a female animal, and sometimes an object to which feminine characteristics are attributed, such as a ship or a country. A man, and sometimes a male animal, is referred to using he. In other cases, it can be used. (See Gender in English.) The word it can also be used as a dummy subject, concerning abstract ideas like time, weather, etc., or a dummy object of a verb or preposition.

The third-person form they is used with both plural and singular referents. Historically, singular they was restricted to quantificational constructions such as Each employee should clean their desk and referential cases where the referent's gender was unknown. However, it is increasingly used when the referent's gender is irrelevant or when the referent is neither male nor female.

The possessive determiners such as my are used as determiners together with nouns, as in my old man, some of his friends. The second possessive forms like mine are used when they do not qualify a noun: as pronouns, as in mine is bigger than yours, and as predicates, as in this one is mine. Note also the construction a friend of mine (meaning "someone who is my friend"). See English possessive for more details.

Demonstrative

The demonstrative pronouns of English are this (plural these), and that (plural those), as in these are good, I like that. All four words can also be used as determiners (followed by a noun), as in those cars. They can also form the alternative pronominal expressions this/that one, these/those ones.

Interrogative

The interrogative pronouns are who, what, and which (all of them can take the suffix -ever for emphasis). The pronoun who refers to a person or people; it has an oblique form whom (though in informal contexts this is usually replaced by who), and a possessive form (pronoun or determiner) whose. The pronoun what refers to things or abstracts. The word which is used to ask about alternatives from what is seen as a closed set: which (of the books) do you like best? (It can also be an interrogative determiner: which book?; this can form the alternative pronominal expressions which one and which ones.) Which, who, and what can be either singular or plural, although who and what often take a singular verb regardless of any supposed number. For more information see who.

In Old and Middle English, the roles of the three words were different from their roles today. "The interrogative pronoun hwā 'who, what' had only singular forms and also only distinguished between non-neuter and neuter, the neuter nominative form being hwæt".[15] Note that neuter and non-neuter refers to the grammatical gender system of the time, rather than the so-called natural gender system of today. A small holdover of this is the ability of relative (but not interrogative) whose to refer to non-persons (e.g., the car whose door won't open).

Pronouns

Pronouns

Main article: English pronouns

Pronouns are a relatively small, closed class of words that function in the place of nouns or noun phrases. They include personal pronouns, demonstrative pronouns, relative pronouns, interrogative pronouns, and some others, mainly indefinite pronouns. The full set of English pronouns is presented in the following table. Nonstandard, informal and archaic forms are in italics.

			Nominative	Accusative	Reflexive	Independent genitive	Dependent genitive
			(subject)	(object)		(possessive)
First-person	Singular		I	me	myself	mine	my mine (before vowel; archaic) me (esp. BrE)
	Plural		we	us	ourselves ourself	ours	our
Second-person	Singular	Standard	you	you	yourself	yours	your
		Archaic informal	thou	thee	thyself	thine	thy thine (before vowel)
	Plural	Standard	you	you	yourselves	yours	your
		Archaic	ye	you	yourselves	yours	your
		Nonstandard	ye you all y'all youse etc. (see above)	ye you all y'all youse	yeerselves y'all's (or y'alls) selves	yeers y'all's (or y'alls)	yeer y'all's (or y'alls)
Third-person	Singular	Masculine	he	him	himself	his
		Feminine	she	her	herself	hers	her
		Neuter	it	it	itself	its	its
		Epicene	they	them	themselves themself	theirs	their
	Plural		they	them	themselves	theirs	their
Generic	Formal		one	one	oneself		one's
	Informal		you	you	yourself	yours	your
Wh-	Relative and interrogative	For persons	who	whom who		whose†	whose
		Non-personal	what	what
	Relative only		which	which			whose
Reciprocal				each other one another
Dummy			there it	it

Biochemistry, polymers, and technology

 Biochemistry, polymers, and technology

Organic chemistry, of course, looks not only in the direction of physics and physical chemistry but also, and even more essentially, in the direction of biology. Biochemistry began with studies of substances derived from plants and animals. By about 1800 many such substances were known, and chemistry had begun to assist physiology in understanding biological function. The nature of the principal chemical categories of foods—proteins, lipids, and carbohydrates—began to be studied in the first half of the century. By the end of the century, the role of enzymes as organic catalysts was clarified, and amino acids were perceived as constituents of proteins. The brilliant German chemist Emil Fischer determined the nature and structure of many carbohydrates and proteins. The announcement of the discovery (1912) of vitamins, independently by the Polish-born American biochemist Casimir Funk and the British biochemist Frederick Hopkins, precipitated a revolution in both biochemistry and human nutrition. Gradually, the details of intermediary metabolism—the way the body uses nutrient substances for energy, growth, and tissue repair—were unraveled. Perhaps the most representative example of this kind of work was the German-born British biochemist Hans Krebs’s establishment of the tricarboxylic acid cycle, or Krebs cycle, in the 1930s.

But the most dramatic discovery in the history of 20th-century biochemistry was surely the structure of DNA (deoxyribonucleic acid), revealed by American geneticist James Watson and British biophysicist Francis Crick in 1953—the famous double helix. The new understanding of the molecule that incorporates the genetic code provided an essential link between chemistry and biology, a bridge over which much traffic continues to flow. The individual “letters” that make the code—four nucleotides named adenine, guanine, cytosine, and thymine—were discovered a century ago, but only at the close of the 20th century could the sequence of these letters in the genes that make up DNA be determined en masse. In June 2000, representatives from the publicly funded U.S. Human Genome Project and from Celera Genomics, a private company in Rockville, Md., simultaneously announced the independent and nearly complete sequencing of the more than three billion nucleotides in the human genome. However, both groups emphasized that this monumental accomplishment was, in a broader perspective, only the end of a race to the starting line.

DNA is, of course, a macromolecule, and an understanding of this centrally important category of chemical compounds was a precondition for the events just described. Starch, cellulose, proteins, and rubber are other examples of natural macromolecules, or very large polymers. The word polymer (meaning “multiple parts”) was coined by Berzelius about 1830, but in the 19th century it was only applied to special cases such as ethylene (C2H4) versus butylene (C4H8). Only in the 1920s did the German chemist Hermann Staudinger definitely assert that complex carbohydrates and rubber had huge molecules. He coined the word macromolecule, viewing polymers as consisting of similar units joined head to tail by the hundreds and connected by ordinary chemical bonds.

The instrumental revolution

 The instrumental revolution

As far as the daily practice of chemical research is concerned, probably the most dramatic change during the 20th century was the revolution in methods of analysis. In 1930 chemists still used “wet-chemical,” or test-tube, methods that had changed little in the previous hundred years: reagent tests, titrations, determination of boiling and melting points, elemental combustion analysis, synthetic and analytic structural arguments, and so on. Starting with commercial labs that provided an out-source for routine analyses and with pH meters that displaced chemical indicators, chemists increasingly began to rely on physical instrumentation and specialists rather than personally administered wet-chemical methods. Physical instrumentation provides the sharp “eyes” that can see to the atomic-molecular level.

In the 1910s J.J. Thomson and his assistant Francis Aston had developed the mass spectrograph to measure atomic and molecular weights with high accuracy. It was gradually improved, so that by the 1940s the mass spectrograph had been transformed into the mass spectrometer—no longer a machine for atomic weight research but rather an analytical instrument for the routine identification of complex unknown compounds (see mass spectrometry). Similarly, colorimetry had a long history, dating back well into the previous century. In the 1940s colorimetric principles were applied to sophisticated instrumentation to create a range of usable spectrophotometers, including visible, infrared, ultraviolet, and Raman spectroscopy. The later addition of laser and computer technology to analytical spectrometers provided further sophistication and also offered important tools for studies of the kinetics and mechanisms of reactions.

Chromatography, used for generations to separate mixtures and identify the presence of a target substance, was ever more impressively automated, and gas chromatography (GC) in particular experienced vigorous development. Nuclear magnetic resonance (NMR), which uses radio waves interacting with a magnetic field to reveal the chemical environments of hydrogen atoms in a compound, was also developed after World War II. Early NMR machines were available in the 1950s; by the 1960s they were workhorses of organic chemical analysis. Also by this time, GC-NMR combinations were introduced, providing chemists unexcelled ability to separate and analyze minute amounts of sample. In the 1980s NMR became well known to the general public, when the technique was applied to medicine—though the name of the application was altered to magnetic resonance imaging (MRI) to avoid the loaded word nuclear.

Many other instrumental methods have seen vigorous development, such as electron paramagnetic resonance and X-ray diffraction. In sum, between 1930 and 1970 the analytical revolution in chemistry utterly transformed the practice of the science and enormously accelerated its progress. Nor did the pace of innovation in analytical chemistry diminish during the final third of the century.

 Organic chemistry in the 20th century

No specialty was more affected by these changes than organic chemistry. The case of the American chemist Robert B. Woodward may be taken as illustrative. Woodward was the finest master of classical organic chemistry, but he was also a leader in aggressively exploiting new instrumentation, especially infrared, ultraviolet, and NMR spectrometry. His stock in trade was “total synthesis,” the creation of a (usually natural) organic substance in the laboratory, beginning with the simplest possible starting materials. Among the compounds that he and his collaborators synthesized were alkaloids such as quinine and strychnine, antibiotics such as tetracycline, and the extremely complex molecule chlorophyll. Woodward’s highest accomplishment in this field actually came six years after his receipt of the Nobel Prize for Chemistry in 1965: the synthesis of vitamin B12, a notable landmark in complexity. Progress continued apace after Woodward’s death. By 1994 a group at Harvard University had succeeded in synthesizing an extraordinarily challenging natural product, called palytoxin, that had more than 60 stereocentres.

These total syntheses have had both practical and scientific spin-offs. Before the “instrumental revolution,” syntheses were often or even usually done to prove molecular structures. Today they are a central element of the search for new drugs. They can also illuminate theory. Together with a young Polish-born American chemical theoretician named Roald Hoffmann, Woodward followed up hints from the B12 synthesis that resulted in the formulation of orbital symmetry rules. These rules seemed to apply to all thermal or photochemical organic reactions that occur in a single step. The simplicity and accuracy of the predictions generated by the new rules, including highly specific stereochemical details of the product of the reaction, provided an invaluable tool for synthetic organic chemists.

Stereochemistry, born toward the end of the 19th century, received steadily increasing attention throughout the 20th century. The three-dimensional details of molecular structure proved to be not only critical to chemical (and biochemical) function but also extraordinarily difficult to analyze and synthesize. Several Nobel Prizes in the second half of the century—those awarded to Derek Barton of Britain, John Cornforth of Australia, Vladimir Prelog of the Soviet Union, and others—were given partially or entirely to honour stereochemical advances. Also important in this regard was the American Elias J. Corey, awarded the Nobel Prize for Chemistry in 1990, who developed what he called retrosynthetic analysis, assisted increasingly by special interactive computer software. This approach transformed synthetic organic chemistry. Another important innovation was combinatorial chemistry, in which scores of compounds are simultaneously prepared—all permutations on a basic type—and then screened for physiological activity.

Chemistry in the 21st century

 Chemistry in the 21st century

Two more innovations of the late 20th century deserve at least brief mention, especially as they are special focuses of the chemical industry in the 21st century. The phenomenon of superconductivity (the ability to conduct electricity with no resistance) was discovered in 1911 at temperatures very close to absolute zero (0 K, −273.15 °C, or −459.67 °F). In 1986 two Swiss chemists discovered that lanthanum copper oxide doped with barium became superconducting at the “high” temperature of 35 K (−238 °C, or −397 °F). Since then, new superconducting materials have been discovered that operate well above the temperature of liquid nitrogen—77 K (−196 °C, or −321 °F). In addition to its purely scientific interest, much research focuses on practical applications of superconductivity.

In 1985 Richard Smalley and Robert Curl at Rice University in Houston, Tex., collaborating with Harold Kroto of the University of Sussex in Brighton, Eng., discovered a fundamental new form of carbon, possessing molecules consisting solely of 60 carbon atoms. They named it buckminsterfullerene (later nicknamed “buckyball”), after Buckminster Fuller, the inventor of the geodesic dome. Research on fullerenes has accelerated since 1990, when a method was announced for producing buckyballs in large quantities and practical applications appeared likely. In 1991 Science magazine named buckminsterfullerene their “molecule of the year.”

Two centuries ago, Lavoisier’s chemical revolution could still be questioned by the English émigré Joseph Priestley. A century ago, the physical reality of the atom was still doubted by some. Today, chemists can maneuver atoms one by one with a scanning tunneling microscope, and other techniques of what has become known as nanotechnology are in rapid development. The history of chemistry is an extraordinary story.

Understanding Hardware and Software

 

Understanding Hardware and Software

To start your computer science journey, you first need to explore some basic concepts. First, we have hardware and software. Hardware refers to the physical components of a computer, like a screen, keyboard, and mouse. Software, on the other hand, is the collection of programs and instructions that tell the computer what to do.

Imagine a computer as a brain, with hardware as the body and software as the mind. The hardware provides the structure and functionality, while the software gives the computer intelligence and the ability to perform tasks. Just like you need both a body and a mind to function, computers rely on hardware and software working together.

Operating System

An operating system is like the boss of a computer. It manages all the tasks and makes sure everything runs smoothly. It helps you to interact with the computer and use different software and tasks. It controls the screen, keyboard, and other parts of the computer.

Example: Windows, macOS, and Android are examples of operating systems that run on computers and smartphones.

The Discipline of Informatics

 

The Discipline of Informatics

Note that in Europe we tend to use the term “Informatics” to denote the subject known in the USA and elsewhere as “Computer Science” (CS) or “Computing”.

Informatics is the science whose effect can be seen in two ways. It has created the new digital world in which text, images, movies and dynamic models of the real world can be stored, retrieved and manipulated, alongside a virtual world of games and simulation. It has been a major accelerator and often a necessary tool in research and development within all of the other sciences and engineering and created new disciplines in collaboration with them by developing new models of representing domain specific data and novel ways of human interaction with those models.

Informatics has its own corpus of concepts, theories, principles, methods, body of knowledge, and open issues. Through its scientific methods and technological developments, Informatics has brought about transformational change across a range of sectors. It now plays a vital role in every aspect of society, and challenges and affects all professions, disciplines, and school subjects. Its contribution to economic development is widely recognised and it has enabled advances and novel research in many disciplines. Its social impact is apparent in the ubiquitous nature of the World Wide Web and its further exploitation in the Internet of Things. Its scientific relevance is backed up by about 2 million peer-reviewed articles (out of an estimated overall total of 70 million) published in academic journals throughout the world since its birth around 60 years ago.

The Future Is Digital

 

The Future Is Digital 

The world is becoming digital day by day. Today, every job is performed with some kind of technology involved. Be it a doctor with the most recent machines or an artist with digital art, everything has technology in it.

Today, technology is one of the fastest-growing careers. Among them, programmers, data analysts, and cybersecurity experts have become extremely in demand.

Nowadays, even jobs outside of tech—like marketing, education, and healthcare—are using computer skills. Also, quite basic coding knowledge can open doors to exciting opportunities. Not just about writing code, though, but understanding how technology shapes the world. 

Why Informatics Education

Through Informatics, the digital world is developed and that this must be safe, secure and just. Currently many developments involving Informatics are shaping medicine, education, transport, etc. and pupils need to be attuned to that and to the tremendous opportunities that exist; such potential will only increase in the future.

Informatics education is fundamental to modern education. Techniques such as interaction, simulation and modeling, algorithm development, visualization, communication, searching capabilities, remote access to web sites, machine translation, machine learning can be used to enhance learning across all disciplines leading to a deeper understanding and appreciation of all disciplines.

What is computer science?

 

What is computer science?

Generally, computer science is defined as the study of computers and computational systems. In most cases, professional computer scientists work with software and software systems, instead of physically tinkering with the machines like their electrical and computer engineering counterparts.

Essentially, this means that computer scientists are more concerned with what is happening on the screen rather than what is happening inside the computer.

There are many areas of study within the field of computer science, including and not limited to, artificial intelligence, database management, software engineering, programming languages, computer security, vision and graphics, and computer systems and networks.

When it comes to the most integral part of computer science, coding or programming is the backbone of the field, being utilized to assist scientists in solving a wide range of tasks.

Computer science can appear very confusing on the surface because it deals with various abstract topics, such as physics, mathematical equations, and computer-based theories.

However, it is primarily focused on finding what is possible and impossible to do using a computer. Commonly, computer scientists will work closely with businesses, organizations, and individuals to improve their products, projects, or websites by using coding or by operating different forms of software.

 

Earth's Edible Treasures

Spices have shaped history, influenced today’s global trade, and even sparked wars! Curious about how spices came to be? It is the hunt for spices that has led Europeans to explore oceans and lands. Today’s global trade routes were established by the search for spices. Continue reading about their history in "A Brief History of Spices"!

Spices come from plants or trees. They are usually in the dried form—they can be harvested from fruits (pepper), bark (cinnamon), roots (ginger), or seeds (coriander seeds). Spices may be whole or powdered. Spice powders may have one or more spices roasted and blended. They can be used as seasoning. You can also make spice blends and hot sauces (Curious about the chemistry of hot sauce? Continue on to "The Science of Hot Sauce: What Makes It Spicy?").

Spices make us think of the kitchen. In the kitchen, they add smell, taste, color, flavor, richness, complexity, and more to food (and drinks: read more about their use in tea and drinks in the Meg A. Mole Interview with Joseph Wiener). The properties of the spices are because of the essential oils they contain (read more in "Spice Up Your Senses: Scent-sational Essential Oils".). Herbs are also used for adding flavor. But they are the leafy portion—like cilantro (leaves) is the herb vs coriander seeds are the spice.

Spices are used in aromatherapy (use of smells for better health; lavender), in making perfumes (anise), medications (capsaicin), incense (cinnamon), cosmetics (turmeric), as insect or animal repellents (garlic/peppermint), home décor (scented wreaths), in religious rituals (cumin), and for their many health benefits (fennel for digestion). They are used in home remedies, too. Cloves are often used for toothaches. They contain a chemical, called eugenol, that naturally soothes pain. However, one small difference in their structure can drastically change their flavor, smell, and how they are used (perform the activity "Small Changes in Structure can Lead to Big Changes in Fragrance" to learn more).

Now you know how spices have many purposes in our everyday lives. They are treasures that also remedy some health issues. But, as always, consume them in moderation. You are now invited to explore the world of spices. You will learn where they come from, how they act, and have fun in the process of finding out all about their hidden lives!

 

A Brief History of Spices

Spices are as old as humankind itself! They have led to the creation and loss of empires. Even new continents were discovered because of spices. There are numerous spices mentioned in the Bible, such as mint, dill, and cumin. Mohammed in the Koran co-owned a shop that stocked spices. In the Hindu Vedas, chilies are spoken of as the child of the Fire God. Spices have a lot of history! But where do they come from?

Early humans accidentally discovered that food wrapped in certain leaves tasted better or even spoiled less quickly. Nuts, stems, seeds, fruits, leaves, roots, bark, etc. were used similarly. The best spices were often hard to find. The search and demand for spices often made huge changes to how people lived and did business.

Spices were highly sought after by the countries in Western Europe. Asian and Mediterranean countries were the places that grew spices at the time. Selling spices was a profitable business. The countries with the spices as well as the European merchants profited from them. Europeans took spices back with them on camels along a network of trade routes called the Silk Road. The Silk Road thus impacted many countries like China, India, Egypt, Persia (Iran today), Arabia, and Rome.

By this time, Europe was starting to use more and more spices. This created a demand, causing spices to become more costly. Spice sellers were in it for the money. The Spanish, Portuguese, English, French, and Dutch all competed for spices and resources in Asia and the Middle East. Wealthy merchants looked for ways to quickly reach the regions where spices were abundant. To meet that demand, the Western Europeans sailed long distances to bring back more spices as they could become rich. Several of the trips ended up finding people, lands, and spice treasures unknown to Western Europe. Christopher Columbus on one such travel accidentally landed on an island in the Americas.

Scientific advances in growing techniques have made growing spices in other parts of the world possible. With the many routes for spice transport, spices became more common. Their prices eventually began to fall. But the complicated history and the global impact remain. The lasting flavors, colors, and scents of spices continue to find new valuable uses today in cooking, religion, medicine, perfumery, and more.

Today, we use spices in everyday things and in more interesting ways. What is your favorite spiced item? Cinnamon rolls? Wasabi ice cream or chile chocolate? Or turmeric and pepper in milk, maybe?

 

The Meaning of Force

A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force. Forces only exist as a result of an interaction.

Contact versus Action-at-a-Distance Forces

For simplicity sake, all forces (interactions) between objects can be placed into two broad categories:

• contact forces, and
• forces resulting from action-at-a-distance

Contact forces are those types of forces that result when the two interacting objects are perceived to be physically contacting each other. Examples of contact forces include frictional forces, tensional forces, normal forces, air resistance forces, and applied forces. These specific forces will be discussed in more detail later in Lesson 2 as well as in other lessons.

Action-at-a-distance forces are those types of forces that result even when the two interacting objects are not in physical contact with each other, yet are able to exert a push or pull despite their physical separation. Examples of action-at-a-distance forces include gravitational forces. For example, the sun and planets exert a gravitational pull on each other despite their large spatial separation. Even when your feet leave the earth and you are no longer in physical contact with the earth, there is a gravitational pull between you and the Earth. Electric forces are action-at-a-distance forces. For example, the protons in the nucleus of an atom and the electrons outside the nucleus experience an electrical pull towards each other despite their small spatial separation. And magnetic forces are action-at-a-distance forces. For example, two magnets can exert a magnetic pull on each other even when separated by a distance of a few centimeters. These specific forces will be discussed in more detail later in Lesson 2 as well as in other lessons.

Examples of contact and action-at-distance forces are listed in the table below.

Contact Forces	Action-at-a-Distance Forces
Frictional Force	Gravitational Force
Tension Force	Electrical Force
Normal Force	Magnetic Force
Air Resistance Force
Applied Force
Spring Force

 

 

The Newton

Force is a quantity that is measured using the standard metric unit known as the Newton. A Newton is abbreviated by an "N." To say "10.0 N" means 10.0 Newton of force. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. Thus, the following unit equivalency can be stated:

1 Newton = 1 kg • m/s2

 

Newton's First Law

In a previous chapter of study, the variety of ways by which motion can be described (words, graphs, diagrams, numbers, etc.) was discussed. In this unit (Newton's Laws of Motion), the ways in which motion can be explained will be discussed. Isaac Newton (a 17th century scientist) put forth a variety of laws that explain why objects move (or don't move) as they do. These three laws have become known as Newton's three laws of motion. The focus of Lesson 1 is Newton's first law of motion - sometimes referred to as the law of inertia.

 

Newton's first law of motion is often stated as

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

 

 

Two Clauses and a Condition

There are two clauses or parts to this statement - one that predicts the behavior of stationary objects and the other that predicts the behavior of moving objects. The two parts are summarized in the following diagram.

 

The behavior of all objects can be described by saying that objects tend to "keep on doing what they're doing" (unless acted upon by an unbalanced force). If at rest, they will continue in this same state of rest. If in motion with an eastward velocity of 5 m/s, they will continue in this same state of motion (5 m/s, East). If in motion with a leftward velocity of 2 m/s, they will continue in this same state of motion (2 m/s, left). The state of motion of an object is maintained as long as the object is not acted upon by an unbalanced force. All objects resist changes in their state of motion - they tend to "keep on doing what they're doing."

There is an important condition that must be met in order for the first law to be applicable to any given motion. The condition is described by the phrase "... unless acted upon by an unbalanced force." As the long as the forces are not unbalanced - that is, as long as the forces are balanced - the first law of motion applies. This concept of a balanced versus and unbalanced force will be discussed in more detail later in Lesson 1.

 Suppose that you filled a baking dish to the rim with water and walked around an oval track making an attempt to complete a lap in the least amount of time. The water would have a tendency to spill from the container during specific locations on the track. In general the water spilled when:

• the container was at rest and you attempted to move it
• the container was in motion and you attempted to stop it
• the container was moving in one direction and you attempted to change its direction.

The water spills whenever the state of motion of the container is changed. The water resisted this change in its own state of motion. The water tended to "keep on doing what it was doing." The container was moved from rest to a high speed at the starting line; the water remained at rest and spilled onto the table. The container was stopped near the finish line; the water kept moving and spilled over container's leading edge. The container was forced to move in a different direction to make it around a curve; the water kept moving in the same direction and spilled over its edge. The behavior of the water during the lap around the track can be explained by Newton's first law of motion.

 

Speed and Velocity

Velocity as a Vector Quantity

Velocity is a vector quantity that refers to "the rate at which an object changes its position." Imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. While this might result in a frenzy of activity, it would result in a zero velocity. Because the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity. If a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. Every step must go into moving that person further from where he or she started. For certain, the person should never change directions and begin to return to the starting position.

Velocity is a vector quantity. As such, velocity is direction aware. When evaluating the velocity of an object, one must keep track of direction. It would not be enough to say that an object has a velocity of 55 mi/hr. One must include direction information in order to fully describe the velocity of the object. For instance, you must describe an object's velocity as being 55 mi/hr, east. This is one of the essential differences between speed and velocity. Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware.

Determining the Direction of the Velocity Vector

The task of describing the direction of the velocity vector is easy. The direction of the velocity vector is simply the same as the direction that an object is moving. It would not matter whether the object is speeding up or slowing down. If an object is moving rightwards, then its velocity is described as being rightwards. If an object is moving downwards, then its velocity is described as being downwards. So an airplane moving towards the west with a speed of 300 mi/hr has a velocity of 300 mi/hr, west. Note that speed has no direction (it is a scalar) and the velocity at any instant is simply the speed value with a direction.

Calculating Average Speed and Average Velocity

As an object moves, it often undergoes changes in speed. For example, during an average trip to school, there are many changes in speed. Rather than the speed-o-meter maintaining a steady reading, the needle constantly moves up and down to reflect the stopping and starting and the accelerating and decelerating. One instant, the car may be moving at 50 mi/hr and another instant, it might be stopped (i.e., 0 mi/hr). Yet during the trip to school the person might average 32 mi/hr. The average speed during an entire motion can be thought of as the average of all speedometer readings. If the speedometer readings could be collected at 1-second intervals (or 0.1-second intervals or ... ) and then averaged together, the average speed could be determined. Now that would be a lot of work. And fortunately, there is a shortcut. Read on.

 

The average speed during the course of a motion is often computed using the following formula:

In contrast, the average velocity is often computed using this formula

Let's begin implementing our understanding of these formulas with the following problem:

Q: While on vacation, Lisa Carr traveled a total distance of 440 miles. Her trip took 8 hours. What was her average speed?

To compute her average speed, we simply divide the distance of travel by the time of travel.

That was easy! Lisa Carr averaged a speed of 55 miles per hour. She may not have been traveling at a constant speed of 55 mi/hr. She undoubtedly, was stopped at some instant in time (perhaps for a bathroom break or for lunch) and she probably was going 65 mi/hr at other instants in time. Yet, she averaged a speed of 55 miles per hour. The above formula represents a shortcut method of determining the average speed of an object.