October 20, 2017

Fizyka: Maszyny proste

Dźwignia jednostronna i dwustronna

Iloczyn długości jednego ramienia i wartości siły działającej na ramię jest równy iloczynowi długości drugiego ramienia i wartości siły działającej na drugie ramię:

r₁󠀳󠁃 · F₁ = r₂ · F₂

Dźwignia jednostronna:
Source: eSzkola.pl
Dżwignia dwustronna:
Source: eSzkola.pl

Blok nieruchomy i ruchomy

Iloczyn długości ramienia i wartości siły działającej na ramię jest równy iloczynowi długości ramienia i wartości siły działającej na drugie ramię:


r · F₁ = r · F₂

Przy podnoszeniu lub opuszczaniu ciała za pomocą bloku nieruchomego nie smienia się wartość siły - zmienia się jedynie jej zwrot.

Source: e-fizyka.info
Wartość śiły, jaką należy przyłożyć, stosując blok ruchomy, jest dwa razy mniejsza niż ciężar podnoszonego ciała.

Source: e-fizyka.info

Kołowrót


Im dłuższa korba (w prównaniu z długością promienia wału), tym mniejszą siłę należy przyłożyć, aby obrócić wał kołowrotu. Warunek równowagi dla kołowrotu można zapisać następująco:

r · F₁ = R · Q
Source: eSzkola.pl

Równia pochyła


Wartość siły, którą należy działać, przesuwając ciało na równi jest tyle mniejsza od wartości jego ciężaru, ile razy wysokości jego ciężaru, ile razy wysokość równi jest mniejsza od jej długości.

T/Q = h/l
Source: fizyka.edu.pl

October 16, 2017

Taiwan in 17th century 十七世紀的台灣

1554 - Ilha Formosa - 葡萄牙人航海經過台灣海峽,看至台灣島而讚歎它的美麗,稱它做 Ilha Formosa

1624 - 荷蘭人來到大員(台南安平)Zeelandia

Source: fortalezas.org
1624 - 1661 - The Dutch occupy Taiwan

1625 - 荷蘭人到赤崁樓(台南市)Provintia

1626 - 1642 - Spain occupies northern Taiwan

1638 - 清朝打敗鄭家後,設『台灣府』治裡台灣。台灣成為這個島嶼的固定名稱。

Source: Wikipedia
1818 - 新港文書

August 30, 2017

Biology: Fungi

Most fungi are eukaryotes, use spores to reproduce, and are heterotrophs.

Most fungi feed by absorbing food through their hyphae. The hyphae produce and discharge digestive chemicals into a food source, which is broken down into small substances that are absorbed by the hyphae.

Fungi produce spores in fruiting bodies. Most fungi reproduce both asexually and sexually.

Fungi are decomposers that recycle Earth's chemicals.

Hypha - One of many branching, threadlike tubes that make up the body of a fungus.
Budding - A form of asexual reproduction in which a new organism grows out of the body of a parent.
Fruiting body - The reproductive hypha of a fungus.
Lichen - The combination of a fungus and either an alga or an autotrophic bacterium that live together in a mutualistic relationship.


Classification of Fungi

Threadlike Fungi - This group contains about 600 different species of molds, including many common bread molds. These fungi produce spores in their threadlike hyphae.
Source: Emaze
Sac Fungi - This group contains over 30000 diverse species of fungi, including yeast, morels, truffles, and some fungi that cause plant diseases, such as Dutch elm disease. They are called sac fungi because they produce spores in structures that look like sacks. 

Source: Toronto Wildlife
Club Fungi - This group includes about 25000 species of mushrooms, bracket fungi, plant parasites, and puffballs. Club fungi produce spores in structures that look like clubs.

Source: Wikispace
Imperfect Fungi - The 25000 species in this group include this Penicillium, the source of an important antibiotic. The fungi in this group are not known to reproduce sexually.

Source: Wikispace

August 29, 2017

Biology: Algal Blooms

Red tides occur when a population of algae increases quickly in ocean waters. Some algae can produce toxins that poison animals.

Nutrients in a lake or pond build up over time, causing an increase in the amount of algae. An accelerated rate of eutrophication can lead to the deaths of many organisms in the lake or pond.

Algal bloom - The rapid growth of population of algae.
Source: Wikipedia

Red tide - An algal bloom that occurs in salt water.
Source: Wikipedia
Eutrophication - The buildup over time of nutrients in freshwater lakes and ponds that leads to an increase in the growth of algae.
Source: BBC

August 24, 2017

Biology: Viruses

Virus

A virus is a small, nonliving particle that invades and then reproduces inside a living cell. Viruses are nonliving because viruses are not cells. Viruses also cannot make food, take in food, or produce wastes. Viruses can only multiply when they are inside a living cell.

A host is a living thing that provides a source of energy for a virus or an organism. Organisms that live on or in a host and cause harm to the host are called parasites. Almost all viruses act like parasites because they destroy the cells in which they multiply.


Source: botanystudies.com

Structure of Viruses

All viruses have two basic parts: an outer coat that protects the virus and an inner core made of genetic material. A virus's genetic material. A virus's genetic material contains the instructions for making new viruses.
The coat of a virus plays an important role during the invasion of a host cell. This coat is made of proteins. Each virus contains unique proteins in its coat. The shape of the proteins allows the virus's coat to attach to, or lock onto, certain cells in the host.


How Viruses Multiply

After a virus attaches to a cell, it enters the cell. Once inside, a virus's genetic material takes over the cell's functions. The genetic material directs the cell to produce the virus's proteins and genetic material. These proteins and genetic material are then assembled.

Active Viruses

After entering a cell the virus's genetic material takes over the cell's functions, and the cell quickly begins to produce the virus's proteins and genetic material these parts assemble into new viruses. When it is full of new viruses the host cell bursts open and releases the new viruses.

Hidden Viruses

Virus's genetic material becomes part of the cell's genetic material. The virus's genetic material may stay in this inactive state for a long time.

August 16, 2017

Biology: Protists

Animal-like protists, or protozoans, include sarcodines, ciliates, zooflagellates, and sporozoans. Like animals, these protists are heterotrophs. Most protozoans move by using pseudopods, cilia or flagella.

Funguslike protists include water molds, downy mildews, and slime molds. Like fungi, these protists are heterotrophs, have cell walls, and use spores to reproduce.

Plantlike protists, or algae, include euglenoids, dinoflagellates, diatoms, green algae, red algae, and brown algae. Like plants, these organisms are autotrophs.

Image result for protist

Protozoan
- An animal-like protist.

Pseudopod - A "false foot" or temporary bulge of the cell membrane used for feeding and movement in some protozoans.

Contractile vacuole - The cell structure that collects extra water from the cytoplasm and then expels it from the cell.

Cilia - The hairlike projections on the outside of cells that move in a wavelike manner.

Symbiosis - A close relationship between two organisms in which at least one of the organisms benefits.

Mutualism - A type of symbiosis in which both partners benefit from living together.

Spore - A tiny cell that is able to grow into a new organism.

Algae - A plantlike protist.

Pigment - A colored chemical compound that absorbs light, producing color.

July 28, 2017

Chemistry: Chemical Reactions


Observing Chemical Reactions

A chemical reaction produces materials that have different properties than the starting materials had. Each reaction either absorbs or releases energy.

Color change, production of a gas or a precipitate, a change in temperature, or a change in the properties of a substance are all clues that a chemical reaction has taken place.

Chemical reactions occur when chemical bonds are formed or broken.

  • Precipitate - A solid that forms from a solution during a chemical reaction.
  • Exothermic Reaction - A reaction that releases energy in the form of heat.
  • Endothermic Reaction - A reaction that absorbs energy in the form of heat.


Writing Chemical Equations

A chemical equation uses symbols to show the reactants and products of a chemical reaction.

Matter is neither created nor destroyed during a chemical reaction.

Chemical reactions may be classified by the types of changes in reactants and products:
  • Synthesis - A chemical reaction in which two or more simple substances combine to form a new, more complex substance.
  • Decomposition - A chemical reaction that breaks down a compound into simpler products.
  • Replacement reaction - A reaction in which one element replaces another in a compound, or in which two elements in different compounds trade places.

  • Chemical equation - A short, easy way to show a chemical reaction, using symbols instead of words.
  • Subscript - A number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound.
  • Reactant - A substance that enters into a chemical reaction
  • Product - A substance formed as a result of a chemical reaction.
  • Conservation of mass - The principle stating that matter is not created or destroyed during a chemical reaction.
  • Coefficient - A number placed in front of a chemical formula in an equation that indicates how many atoms or molecules of each reactant and product are involved in a reaction.


Controlling Chemical Reactions

Every chemical reaction needs activation energy to get started. Endothermic reactions need energy to continue.

The rate of chemical reaction can be controlled by such factors as concentration, surface area, temperature, and use of a catalyst or inhibitor.

  • Activation energy - The minimum amount of energy needed to start a chemical reaction.
  • Catalyst - A material that increases the rate of a chemical reaction by lowering the activation energy.
  • Inhibitor
  • Concentration - The amount of one material dissolved in a given amount of another material.
  • Enzyme - A biological catalyst that lowers the activation energy of reactions in cells.