100 Greatest Science Discoveries off All Time (Part 1)

Levers and Buoyancy
(Year of Discovery: 260 B.C.)

What Is It?
The two fundamental principles underlying all physics and engineering.

Who Discovered It?
Archimedes

Why Is This One of the 100 Greatest?

The concepts of buoyancy (water pushes up on an object with a force equal to the weight of water that the object displaces) and of levers (a force pushing down on one side of a lever creates a lifting force on the other side that is proportional to the lengths of the two sides of the lever) lie at the foundation of all quantitative science and engineering. They represent humanity’s earliest breakthroughs in understanding the relationships in the physical world around us and in devising mathematical ways to describe the physical phenomena of the world. Count less engineering and scientific advances have depended on those two discoveries.

How Was It Discovered?

LEVER

In 260 B.C. 26-year-old Archimedes studied the two known sciences, astronomy and geometry in Syracuse, Sicily. One day Archimedes was distracted by four boys playing on the beach with a drift wood plank. They balanced the board over a waist-high rock. One boy straddled one end while his three friends jumped hard onto the other. The lone boy was tossed into the air. The boys slid the board off-center along their balancing rock so that only one-quarter of it remained on the short side. Three of the boys climbed onto the short, top end. The fourth boy bounded onto the rising long end, crashing it back down to the sand and catapulting his three friends into the air. Archimedes was fascinated and he determined to understand the principles that so easily allowed a small weight (one boy) to lift a large weight (three boys).

Archimedes used a strip of wood and small wooden blocks to model the boys and their drift wood. He made a triangular block to model their rock. By measuring as he balanced different combination of weights on each end of the lever (lever came from the Latin word meaning “to lift”), Archimedes realized that levers were an example of one of Euclid’s proportions at work. The force (weight) pushing down on each side of the lever had to be proportional to the lengths of board on each side of the balance point. He had discovered the mathematical concept of levers, the most common and basic lifting system ever devised.

BUOYANCY

Fifteen years later, in 245 B.C., Archimedes was ordered by King Hieron to find out whether a goldsmith had cheated the king. Hieron had given the goldsmith a weight of gold and asked him to fashion a solid gold crown. Even though the crown weighed exactly the same as the original gold, the king suspected that the goldsmith had wrapped a thin layer of gold around some other, cheaper metal in side. Archimedes was ordered to discover whether the crown was solid gold without damaging the crown itself.

It seemed like an impossible task. In a public bath house Archimedes noticed his arm floating on the water’s surface. A vague idea began to form in his mind. He pulled his arm completely under the surface. Then he relaxed and it floated back up. He stood up in the tub. The water level dropped around the tub’s sides. He sat back down. The water level rose. He lay down. The water rose higher, and he realized that he felt lighter. He stood up. The water level fell and he felt heavier. Water had to be pushing up on his submerged body to make it feel lighter.

He carried a stone and a block of wood of about the same size into the tub and submerged them both. The stone sank, but felt lighter. He had to push the wood down to submerge it. That meant that water pushed up with a force related to the amount of water displaced by the object (the object’s size) rather than to the object’s weight. How heavy the object felt in the water had to relate to the object’s density (how much each unit volume of it weighed).

That showed Archimedes how to answer the king’s question. He re turned to the king. The key was density. If the crown was made of some other metal than gold, it could weigh the same but would have a different density and thus occupy a different volume. The crown and an equal weight of gold were dunked into a bowl of water. The crown displaced more water and was thus shown to be a fake.

More important, Archimedes discovered the principle of buoyancy: Water pushes up on objects with a force equal to the amount of water the objects displace.

Bone Facts

What would happen if humans didn't have bones?
You'd be floppy like a beanbag. Could you stand up? Forget it. Could you walk? No way. Without bones you'd be just a puddle of skin and guts on the floor. Bones have two purposes. Some, like your backbone, provide the structure which enables you to stand erect instead of lying like a puddle on the floor. Other bones protect the delicate, and sometimes soft, insides of your body. Your skull, a series of fused bones, acts like a hard protective helmet for your brain. The bones, or vertebrae, of your spinal column surround your spinal cord, a complex bundle of nerves. Imagine what could happen to your heart and lungs without the protective armor of your rib cage!

How many bones do humans have?
When you were born you had over 300 bones. As you grew, some of these bones began to fuse together. The result? An adult has only 206 bones!


How do my bones move?
With a lot of help. You need muscles to pull on bones so that you can move. Along with muscles and joints, bones are responsible for you being able to move. Your muscles are attached to bones. When muscles contract, the bones to which they are attached act as levers and cause various body parts to move. You also need joints which provide flexible connections between these bones. Your body has different kinds of joints. Some, such as those in your knees, work like door hinges, enabling you to move back and forth. Those in your neck enable bones to pivot so you can turn your head. Still other joints like the shoulder enable you to move your arms 360 degrees like a shower head.

Are your bones alive?
Absolutely. Bones are made of a mix of hard stuff that gives them strength and tons of living cells which help them grow and repair themselves. Like other cells in your body, the bone cells rely on blood to keep them alive. Blood brings them food and oxygen and takes away waste. If bones weren't made of living cells, things like broken toes or arms would never mend. But don't worry, they do. That's because your bone cells are busy growing and multiplying to repair the break! How? When you break your toe, blood clots form to close up the space between the broken segments. Then your body mobilizes bone cells to deposit more of the hard stuff to bridge the break.

What's bone marrow?
Many bones are hollow. Their hollowness makes bones strong and light. It' s in the center of many bones that bone marrow makes new red and white blood cells. Red blood cells ensure that oxygen is distributed to all parts of your body and white blood cells ensure you are able to fight germs and disease. Who would have thought that bones make blood!?!


Do all critters have a backbone?
Nope. In fact, some 97% of critters on earth don' t have a backbone or spine. Remarkably enough, of those that do have a backbone, there are lots of similarities: a skull surrounding a brain, a rib cage surrounding a heart, and a jawbone or mouth opening.

Factoids

• The human hand has 27 bones; your face has 14!

• The longest bone in your body? Your thigh bone, the femur, it' s about 1/4 of your height.

• The smallest is the stirrup bone in the ear which can measure 1/10 of an inch.
  

• Did you know that humans and giraffes have the same number of bones in their necks? Giraffe neck vertebrae are just much, much longer!
  

• You have over 230 moveable and semi-moveable joints in your body.

CAUSE AND EFFECT OF ACID RAIN

"Acid rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. Acidic rain is caused mainly by dissolution of sulfur dioxide, nitric acid and hydrochloric acid. These pollutants originate from human activity such as the combustion of burnable waste and fossil fuels within thermal power plants and automobiles (Kita et al., 2004).

Rain that presents a concentration of H⁺ ions greater than 2.5 μeq⁻¹ and pH values lower than 5.6 is considered acid (Evans, 1984). Galloway et al. (1982) proposed a pH of 5.0 as a limit of natural contribution. Rain with a sufficiently low pH to cause damage to plants had been registered near industrial sources.

The principal natural phenomena that contribute acid-producing gases to the atmosphere are emissions from volcanoes and those from biological processes that occur on the land, in wetlands, and in the oceans. The major biological source of sulphur containing compounds is dimethyl sulphide.

Acid rain has been shown to have adverse impacts on forests, freshwaters and soils, killing off insect and aquatic lifeforms as well as causing damage to buildings and having possible impacts on human health. Both the lower pH and higher aluminium concentrations in surface water that occur as a result of acid rain can cause damage to fish and other aquatic animals. At pHs lower than 5 most fish eggs will not hatch and lower pHs can kill adult fish. As lakes become more acidic biodiversity is reduced. Acid rain has eliminated insect life and some fish species, including the brook trout in some Appalachian streams and creeks.

Like many environmental problems, acid deposition is caused by the cumulative actions of millions of individual people. Individuals can contribute directly by conserving energy, since energy production causes the largest portion of the acid deposition problem.

References:

Evans, 1984 L.S. Evans, Botanical aspects of acidic precipitation, Bot. Rev. 50 (1984), pp. 449–490.

Galloway et al., 1982 J.N. Galloway, G.E. Likens, W.C. Keene and J.M. Miller, The composition of precipitation in remote areas of the world, J. Geophys. Res. 87 (1982), pp. 8771–8786.

Kita et al., 2004 I. Kita, T. Sato, Y. Kase and P. Mitropoulos, Neutral rains at Athens, Greece: a natural safeguard against acidification of rains, Sci. Total Environ. 327 (2004), pp. 285–294.

71–80.

http://asd-www.larc.nasa.gov/biomass_burn/glossary.html

http://www.saag.org/%5Cpapers20%5Cpaper1944.html

http://www.epa.gov/acidrain/effects/forests.html

http://www.epa.gov/acidrain/

THE EXCLUSIVE AND NON EXCLUSIVE MANGROVE SPECIES

Mangrove forests are typical of tropical and subtropical regions, where they replace the temperate salt- marshes. It has been estimated that around 75% of all sheltered tropical shores were at one time fringed with mangrove, a figure that suggests their tremendous importance. The indo-west pacific region has the world’s most extensive mangrove forests with by far the largest number of mangrove species. Mangrove forest extend as far as 320km (200 mi) inland in southern New Gueinea and some islands in Indonesia, where the influence of the tides extend far up estuaries.

There are 84 species recorded through out the whole region. From that number, only 48 species are the true Asian species (Matsubara, 2003) found in the indo-pacific region. From the whole species of 48, there is only 34 of it has been identified for its type: exclusive and non-exclusive. This is due to the lack of studies about the mangrove. From this, little information can be obtained.

Figure 1: Geographic distribution of mangroves forest

Table1: The type and gegraphical region found of mangrove species

No	Mangrove sp.	Region Found						Type
		1	2	3	4	5	6	Exclusive	Non-Exclusive
1	Acrostichum aureum	+	+	+	+	+	+		√
2	Acrostichum danaeifolium	+	+						√
3	Acrostichum speciosum					+	+		√
4	Acanthus ebrecteatus					+	+	√
5	Acanthus illicifolius					+	+	√
6	Aegiceras corniculatum					+	+	√
7	Avicennia alba					+	+	√
8	Avicennia germinans	+	+	+				√
9	Avicennia marina				+	+	+	√
10	Barringtonia racemosa				+	+	+		√
11	Brownlowia argentata					+	+		√
12	Brownlowia tersa					+			√
13	Brugueira cylindrica					+	+	√
14	Brugueira gymnorhiza				+	+	+	√
15	Brugueira parviflora					+	+	√
16	Brugueira sexangula					+	+	√
17	Ceriops decandra					+	+	√
18	Cerbera floribunda						+		√
19	Cerbera manghas					+	+		√
20	Clerodendrum inerme				+	+	+		√
21	Exoecaria agallocha				+	+	+		√
23	Heriteria littoralis				+	+	+		√
24	Hibiscus tiliaceus	+	+	+	+	+	+		√
25	Kandelia candel					+		√
26	Lumnitzera racemosa				+	+	+	√
27	Lumnitzera littorea					+	+	√
28	Nypa fructicans		+	+		+	+	√
29	Pemphis acidula				+	+	+		√
30	Rhizophora mucronata					+	+	√
31	Rhizophora apiculata				+	+	+	√
32	Scyphihora hydrophyllacea				+	+		√
33	Soneratia alba				+	+	+	√
34	Soneratia caseolaris					+	+	√
35	Soneratia ovata					+	+	√
36	Thespesia populnea	+	+	+	+	+	+		√
37	Xylocarpus moluccensis				+	+	+		√
38	Xylocarpus granatum				+	+	+	√

From the data, the most abundance of mangrove community is obtained by region five which is the indo-pacific; while the mangrove species are compose of many of associatetype than non-associate. The most abundant species is Thespesia populnea, Hibiscus tiliaceus and Acrostichum aureum which is all is non- exclusive type of mangrove.

References:

Castro, P. and Huber, M.E.2007. Marine Biology, 6^th Edition. McGraw-Hill Companies, Inc. 460pp.

Matsubara,J.2003. The role of the mangrove in a coast ecosystem,APEC 2003 Sister School Networking in Thailand.