Some people think physics is too much trouble because the formula used. "Aja Ngapalin difficult formula, udah gitu gimana confused makenya want", so comments about the physics students. Actually, the formula does not need to be memorized, but understood. It sounds cliche, but true.

Formulas or equations in physics, is generally used as a succinct statement of the concept. A theory or concept that could take the explanation sheets of paper, can be expressed exactly in a single line equation. This is one main reason why in a lot of physics formulas.

However, many things happen in our education is that most students only see the formulas that are in fragments. They do not (want to) know the story or concept behind these formulas. This results in the analysis of weak students, so they can only solve the immediate problem and that is easy to use only one formula. If there are problems using the concept of different-which means also using more than one formula-they confusion finish.

Here are some examples of the confusion of the students of the formula in physics:

1) The formula for the coefficient of static friction is often expressed by:

μ = tan θ ..........( 1)

This formula is often the students understood that the coefficient of static friction (μ) depending on the size of the field angle (θ). Yet this understanding was wrong. The coefficient of static friction depends only on the type of materials that rub together. Or in the language of physics, the coefficient of static friction is characteristic of the rubbing of two materials (eg, between the wood with wood, etc.).

Formula (1) is a formula that is used as a way to measure the coefficient of friction. If we have an object, such as books, then we want to know how the coefficient of static friction between the book with the surface of the wood, so I know it is to put the book on a wooden surface. Then our wood surface angle (the horizontal) bit by bit. At the beginning (small angle), the book will not move, but after continued to tilt, at a certain angle (θ) the book will begin to start moving, never tan θ which is the value of μ.

Seen that the value of angle θ is special, can not be varied at random, there is only one value of θ for the coefficient of static friction between the paper and wood materials. This resulted in the formula (1) can not be understood as a relationship of dependence between θ μs. Formula that tells us how to measure μ.

2) Another example is the formula for the long expansion coefficient α:

α = ΔL / (ΔT.Lo) ........( 2)

In the above formula, if α depends on changes in body length ΔL, ΔT the temperature change, or the initial length Lo? The answer: α is not dependent on the three quantities above. Again, the long expansion coefficient α is a characteristic of a material (metal). Pers. (2) is an equation which defines the long expansion coefficient. Thus, the meaning of the press. (2) is a long expansion coefficient is defined as the fractional change in length per unit temperature.

3) Others again with free fall equations below,

h = - (gt ^ 2) / 2 .............( 3)

who was declared the dependence height h versus time t. Pers. (3) is the equation of the function h ^ t 2.


The students often do not know the "story" behind the formula. So that their understanding is often wrong, that every formula is only understood as a dependence relationship between variables. From the example above, we can know that the formula can be stated:
a) how to measure something
b) the definition of a quantity
c) function (dependence) of a variable to another variable.

To understand a formula we need to understand the story behind the formula they will be.

Aspartame is an artificial sweetener from the non-sugar groups that sakarida widely used for diet products or low-calorie products. Aspartame is sweeter about 180-200 times than regular sugar with the same concentration. This means that by using these sweeteners, we only need 1 / 200 times less aspartame than using regular sugar.

Aspartame is none other than the methyl esters of natural amino acids dipeptida namely aspartic acid and phenylalanine. Aspartame is found by accident by James Schlatter, a chemist at GD Searle Co. in 1965. Schlatter has unexpectedly synthesize aspartame at the time he made anti-pain medication.

Aspartame Synthesis
There are 3 reagents required for the synthesis of aspartame, methanol, phenylalanine, and aspartic acid. Starting materials needed to make the aspartame is rasemat mixture of phenylalanine, L-phenylalanine only be used for synthesis. L and D isomers of phenylalanine are separated by the addition Ac2O and NaOH, the reaction was then reacted with Porcine Kidney Acylase and then extracted with organic solvents followed by pickling. D-phenylalanine will be located in the organic phase whereas the L-phenylalanine will be found in the water phase.

Clusters acid L-phenylalanine is then converted into methyl esters using methanol and HCl.Last reacting methyl esters of phenylalanine with aspartic acid to produce dipeptida structure. This stage because it requires several stages of acid functional groups on the aspartic acid must be protected so as not to react, we need only one of two aspartic acid functional groups which will react with amine functional groups on the phenylalanine methyl ester.
The nature of Chemical Aspartame
Aspartame has the chemical formula C14H18N2O5 and molecular weight 294.31 Aspartame has two functional groups that can be ionized and both there at the residues aspartic acid. At neutral pH, aspartame is in two forms ionized. Aspartame is stable maximum at pH 4.3. Aspartame at room temperature form of white powder that does not smell and point leburnya 248-2500C. 

Why Aspartame is called Sugar With 0 Calories?
In order for us to know why aspartame is called 0-calorie sugar then let us do a simple calculation. Suppose a product bottled beverages with 330 mL of sugar requires 50 grams for a certain sweetness level in accordance with the standard drink, so by using aspartame we only need: (we use the level of sweetness of aspartame is 200 times that of regular sugar)

Grams of aspartame are required:

= 1 / 200 x 50 g

= 0.25 g

Aspartame is metabolized in the body into their constituent components namely aspartic acid, phenylalanine, and methanol. Like other amino acids, each gram of amino acid is metabolized in the body to produce 4 calories, because we have then 0.25 g of aspartame:

Mol aspartame

= 0.25 / 294.31

= 8.5 x10-4 mol

Aspartame breakdown reaction to constituent:

C14H18N2O5 + 3H2O +2 H + -> C4H7NO4 + C9H11NO2 + CH3OH + H2O

Comparison mol aspartic acid and phenylalanine is 1:1 then the mass of each of these amino acids are:

Aspartic acid

= 8.5 x10-4 mol x 133 = 0.11 g

Phenylalanine

= 8.5 x10-4 mol x 165 = 0.14 g

Calories produced are:

= (0.11 g + 0.14 g) x 4 = 1 calorie

From the above calculation can be seen that by consuming beverages using aspartame as a sweetener, we only get just 1 calorie. This is tantamount to saying calories can ignore it because it was the aspatam can be used as a substitute for sugar with 0 calories.

Reference:

• http://www.3dchem.com/molecules.asp?ID=24#
• http://www.chemistrydaily.com/chemistry/Aspartame
• http://www.chm.bris.ac.uk/webprojects2000/srogers/sarah.html
• http://www.elmhurst.edu/~chm/vchembook/549aspartame.html
• http://chemicalland21.com/lifescience/foco/ASPARTAME.htm