How Does A Fan Work?
The Fan is an electronic device that everybody use it in their house. People use the fan to
make the air in the room cooler, especially in hot day. However ,do you know how a fan
works?
An electric fan has an electric motor with some fan blades attached to its rotating shaft. As
the motor spins, the fan blades rotate. Each blade is angled a bit, and as the inclined plane of
the blade moves through the air, it forces the air ahead of it forward. Each blade does this on
a continuous basis, and the result is a moving air stream. The fan is taking air from the area
behind itself and blowing it out the front.
The fan generates a movement of air, causing the warm dense air to descend, and the cool
dense air to rise, thus creating a feeling of coolness in the air.
Latihan
Biodiesel is a clean burning substitute for petroleum based diesel fuel. Biodiesel is made of vegetable
oil.
To make or manufacture Biodiesel, you must first start with raw materials. The raw materials needed
in the production of Biodiesel are a small amount of methanol and a ready supply of vegetable
product. One of the most common vegetables used in the production of Biodiesel is corn, although
depending on the geographic location of the manufacturing facility many other plants are used as
well (rapeseed, soybeans, flaxseed, etc.). The first step is to use the raw vegetable product to make
vegetable oil. Vegetable oil by itself will not be what you need to power a car, from here it has to be
processed into Biodiesel.
The process for converting vegetable oil into Biodiesel is sometimes called ester interchange. To
complete this process the vegetable oil has to be combined with a smaller amount of methanol and
then put in the presence of a small quantity of an alkaline catalyst (for example, 5% to 1% sodium
hydroxide). Vegetable oil is made up of so-called triglycerides, which is a compound of the trivalent
alcohol glycerin with three fatty acids. The goal of ester interchange is to separate the glycerin
molecule from the three fatty acids and replace it with three methanol molecules. This process then
yields roughly 90% Biodiesel and 10% of a glycerin byproduct. The glycerin byproduct can be used in
a number of other chemical processes for different industries.
1. What is the text about?
A. The process of making Biodiesel
B. The use of the Biodiesel.
C. The advantage of using the Biodiesel.
D. The benefit of producing the Biodiesel.
E. The development of the Biodiesel product.
2. What are interchanged in the process of ester interchange?
A. The three fatty acids with the glycerin molecules.
B. The glycerin molecule with three methanol molecules
C. Methanol with the three fatty acids.
D. Vegetable oil with methanol
E. Methanol and alkaline catalyst.
3. According to the text, one of the advantages in using biodiesel is…
A. it is cheap.
B. it only uses vegetable oil.
C. it uses replaceable materials.
D. it can be done in small industry.
E. it gives less pollution than petroleum
4. “The process for converting vegetable oil…”(Paragraph 3). The word “converting” is
closest in meaning to…
A. Producing
B. Separating
C. Attaching
D. Processing
E. Changing
