Backwards swimmer - Snapple Real fact #41

Did You know?

Shrimp can only swim backward.

Shrimp do not have fins to move in the water so they pull in their abdomen toward their body quickly. This motion propels them through the water but because of their configuration it means they are moving backwards.

Credits: Wikianswers

Exponential fractions (1)

Geometric series

Unknown negative integer

Questions

Elementary Algebra as I know it

Primary school exam papers all have a select set of questions to differentiate between those who are better than the others. From my knowledge, the 2 topics: "Algebra" and "Simultaneous Equations" are the solutions for some of these problems. These 2 topics can even be applied to normal everyday maths questions to help solve them more easily. However, these 2 topics are not taught in primary school. Hence, i will try my best to create a simple guide to algebra for primary school students to understand.


Algebra
Algebra is the use of letters (any letter to your liking) to denote unknowns, say an amount of sugar (i.e -- x kg of sugar). Before learning to apply algebra to solve your problem sums, you have got to understand how algebra interacts with mathematical signs and numbers.

1) Letters of the same kind can be added/subtracted together.
- x + x = 2x
- 3a + 4a = 7a
- 10r - 4r = 6r
- 3b + 4b - b = 6b

2) 2 different kind of letters cannot be added/subtracted together

- ( a + b) will still remain as ( a + b)
- x + 4y = x +4y
- 2a + 4a - 3b + 5b - a = 5a + 2b


3) Letters in algebra can be multiplied by any number or letter.

- 3 x b = 3b
- 3a x 6b = 18ab
- 2a x 4y = 8ay


4) Letters of the same kind in algebra can be divided by each other
- 6a / 2a = 3
- 9b / 3 = 3b
- 2 / 4c = (1/4)c --> one quarter of c
- d / d = 1 ( same logic as 2 / 2 or any number divided by itself)


5) Letters of the same kind in algebra cannot be divided by another different letter.
- a / b = a / b
- c / d = c / d

However..
Letters of the 2 different kind with numbers attached to it can still be divided.

- 6a / 2b = 3a/ b
- 2c / 10d = c / 5d


These are how algebraic letters interact with multiplication signs and numbers. For more enquiries, feel free to post at the tagboard to ask questions.




*extra - a x a = a^2 ( a to the power of 2 or as some may prefer to call it, a-squared)

3x3 Magic Square solution

Surely you've come across magic squares. Here's a 3 x 3 magic square. It's really easy to solve and remember.

2 9 4
7 5 3
6 1 8


Here's how i remember the order of the numbers in an empty box:
The even numbers 2, 4, 6, 8 take up each corner of the box with 5 in the middle of the box. The odd numbers take up the remainder empty spots.
Keeping in mind that each row/column/diagonal adds up to 15, it should be pretty easy to figure out which spots the odd numbers belong to since we've already filled up 5/9 of the box.


Perhaps you're wondering why each side should add up to 15. Adding up all the numbers from 1 to 9 will give a result of 45. Since the additions involves 3 numbers, divide 45 by 3 and you get 15. 15 is therefore the average sum of the 3 numbers you add up. This rule can also be applied to other magic squares.

Beyond Human Frequency - Snapple "Real Fact" #48

Did You Know?

Fact: Cats can hear ultrasound.

Ultrasound is the frequency of sound waves greater than what the human ear can hear (approximately 20kHz). Cats have an approximate hearing range of 45Hz - 64,000Hz compared to 65Hz - 20,000Hz of a human hearing range.

*Infrasound is any frequency below the average human hearing range.

The Straight Dope and Real Facts

I've been drinking Snapple recently and i've kept the caps containing "Real Facts". Every cap has a different fact and SO, i'm going to keep track of what i have collected here and perhaps do some extra read up regarding the facts.

As i was surfing the web, i came across this website The Straight Dope.com. It's a website (by a person called Cecil Adams) that contains MANY questions and answers and some other random bits of information that may intrigue you. Claiming to be the smartest human on Earth, why not go check out what he has to offer you?

Pink Flamingos - Snapple "Real Fact" #11

Did You Know?

Fact: Flamingos turn pink from eating shrimps.

Shrimps contain red pigments classified as carotenoids which is found in carrots too! A lack of carotenoids in the diet of a zoo-kept flamingo may turn a flamingo white.

Esters

Question: Work out the number of esters with the molecular formula C4H8O2. - passerby

My reply: Esters have the functional group R-O-CO-R'. My drawing out the compound and permutating the number of ways the functional group can fit into the compound, this is what I get.
By inserting the functional group between the 3rd and 4th carbon atom will yield the same structural formula as (1). Hence, there're only 2 different esters resulting from the C4H8O2 formula. ;)

Bromoethene vs Bromopropene

Question: Suggest an explanation for e unreactivity of Br in bromoethene as compared to 3-bromo-propene - passerby

My reply: Okay, firstly i would assume that you're asking about electrophilic addition for both reactions involving Bromine. Bromine as you know is an electrophile, which is also an electron withdrawing atom. Hence, Br in bromoethene will "spread" the electrons out from the electron rich C=C and stabilises bromoethene. In 3-bromopropene (i'm assuming it's 3-bromo-prop-1-ene), the Br atom is too far away from C=C and hence it does not really "spread" the electrons from the pi bond across the molecule. In this way, the C=C pi bond in 3-bromopropene will be more susceptible to a bromine attack compared to bromoethene.

Iodoform test

The iodoform test (or tri Iodomethane test) is used to identify the presence of 2 particular structural units:


1)RCH(OH)CH3

2)RCOCH3

*R denotes H, alkyl or aryl group


In positive tests, the reaction will produce a yellow precipitate of CHI3.

*Click on picture for a clearer and bigger view

Any compound which contains the above mentioned structural units will result in a positive iodoform test. Ethanol is the only first degree alcohol to give a positive iodoform test. The following are some alcohols which may produce reactions with tri-iodomethane.

The compounds which produced a positive reaction all have the specific functional group [RCH(OH)CH3] and the boxed R-group. Propan-2-ol is unable to give a positive reaction because it does not have a CH3.

Here are the some other compounds which may react with tri-iodomethane:

The compounds which produced a positive reaction all have the functional group [RCOCH3] and a respective R-group boxed in red.

To figure out whether a compound has a positive iodoform reaction, always look out for it's functional group : [RCH(OH)CH3] or [RCOCH3]. If the compound does not have the specific functional group, it simply does not give a positive iodoform test and hence the equations for the reaction is not applicable.

-adapted and extended with permission from http://learnsg.blogspot.com-

Iodoform reactions

Question: Does ethanamide & ethanoic acid give positive iodoform test?




Ans:

Okay, i've drawn up the molecules you asked abt and the required structural units for a positive iodoform test. As you can see, both ethanoic acid and ethanamide DO NOT HAVE either of the 2 structural units in the red box. Therefore the iodoform test will present a negative result.

Area/Volume Formulas

Ever thought of compiling what you've learnt into bite sized information but you're too busy or lazy to make your own copy? Fret not, for here comes the time-savers you need! While i have been preparing for my exams, i've conveniently made my own copies of notes for easier references. It has always been so tedious for me to grab a couple of books and leave it on my table. It makes everything so messy. Here's one of the 'summaries' i've made - this one on Areas and Volumes.

**click on image to enlarge**

(*included - cuboids, closed cylinder, prism, pyramid, cone, sphere, sector, hemisphere)

6 Ways To Boost Brainpower

1) Exercise
Exercise increases blood flow to the brain, which also increases the delivery of oxygen, fuel and nutrients to those hard-working neurons. Research has shown that exercise can increase levels of a substance called brain-derived neurotrophic factor (BDNF), which encourages growth, communication and survival of neurons.

*neurotrophic - relating to or dependent on the influence of nerves on the nutrition of tissue.


2) Diet
The brain is mostly fat—all those cell membranes and myelin coverings require fatty acids—so it is important to eat certain fats, particularly omega-3 fats, which are found in fish, nuts and seeds. Alzheimer’s disease, depression, schizophrenia and other disorders may be associated with low levels of omega-3 fatty acids.

Fruits and vegetables also appear to be brain superfoods. Produce is high in substances called antioxidants, which counteract atoms that can damage brain cells. Researchers have found that high-antioxidant diets keep learning and memory sharp in aging rats and even reduce the brain damage caused by strokes.


3) Stimulants
Small to moderate amounts of stimulants such as caffeine can boost our mental functioning in ways researchers are now measuring. One study showed that the equivalent of two cups of coffee can boost short-term memory and reaction time.


4) Video games
Video games can improve mental dexterity, while boosting hand-eye coordination, depth perception and pattern recognition. Gamers also have better attention spans and information-processing skills than the average Joe has.


5) Music
Music can treat anxiety and insomnia, lower blood pressure, soothe patients with dementia.
But there’s more to music’s interaction with the brain than just the raw sound. Music can also activate your brain’s reward centers and depress activity in the amygdala, reducing fear and other negative emotions.



6) Meditation
Meditation, or the turning of the mind inward for contemplation and relaxation, seems to help all types of conditions—anxiety disorders, sure, but it can also reduce pain and treat high blood pressure, asthma, insomnia, diabetes, depression and even skin conditions.
big boosts in immune system functioning. Meditation can also increase focus and attention, improving performance on cognitive tasks.



Find out more on Scientific American.

Welcome!

The world wide web is but a pool of nigh unlimited information. Surely you have come across a situation whereby you need to find something but you could not get what you want because there is just too much results from a search engine? This blog is created in order to coalesce information which we may need in our daily lives. Future posts may include topics studied in sch, interesting facts, mindmaps and even DIY mini-projects! What the future will bring, only time will tell. For a portal to information, cheers to all! =)