## Recently changed documents

### ramp velocities

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3-Dec-09

ramp velocities

### science fair project yeast growth files

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9-May-09

science fair project yeast growth files

### make graphs online

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9-May-09

make graphs online

### Sun and Tilted Earth

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14-Dec-08

Sun and Tilted Earth

### 26 what tool is used to measure weight?

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23-Sep-08

Weight is measured using a spring balance. Weight is many times confused with mass. Mass can be measured with a simple balance. If you were to use a balance on ground and on the top of a mountain you will get different results.

That is why a spring balance is needed to measure weight which takes into account not only mass but also gravitational pull.

### 24 Does weight change based on gravity?

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23-Sep-08

Weight changes based on gravity. A object is a bit lighter on the top of a tall mountain. An object is much leighter on the surface of a moon. In fact the object has almost no weight in empty space. The object still has mass to it but no weight because there is nothing pulling the object.

### 22 what is weight?

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23-Sep-08

Weight is a measure how heavy something is. How heavy something is depends on two things. One of them is gravity. Something that is heavy on earth might be lighter on the moon as moon has less gravity than earth.

The other one weight depends on is how much mass there is in the object. More mass then more weight.

Because weight is a measure of both mass and gravity one uses a "spring balance" to measure weight. A "spring balance" tells us how much force is applied on the string. This force is proportional to the mass and also the gravity and hence is a measure of its weight.

### 12 what kind of tools can you use to measure physical properties?

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22-Sep-08

```Rulers
Microscopes
thermometers
scales
Balances
```

### 10 what are physical properties of an element?

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22-Sep-08

Here are some physical properties of an element like Iron or Gold.

```Color
Odor
Mass
Texture
Hardness
```

Typically physical properties can be measured with out changing the object.

### 08 what are chemical properties of an element?

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22-Sep-08

Chemical properties of an element describes how it mixes or combines with other elements to form new materials.

### 06 How do you identify an element

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22-Sep-08

An element is identified by its properties. There are two kinds of properties. Chemical properties and Physical Properties.

### 14 what portion of the elements are metals

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22-Sep-08

Most elements are metals. In fact 3 out of every 4 elements are metals. Out of the 102 or so elements, about 75 are metals.

Metals are smooth, shiny, bendable, and conduct heat and electricity well.

### 16 what are some properties of metals

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22-Sep-08

Metals are shiny, bendable, and conduct heat and electricity. Iron, copper, Silver, and Gold are all metals.

### 18 Can metals conduct heat and electricity?

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22-Sep-08

Metals conduct heat and electricity well. Copper is an excellent conductor of electricity. The electrical wiring in a house is made with copper.

### 20 why do you think pans are made of metals?

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22-Sep-08

We use pans to cook. Because of this pans must be able to trasmit heat well to the food. Pans are also smooth and shiny and hard. These are all properties of metals.

### 04 what we see in the world, are they pure elements or combination of elements?

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22-Sep-08

Most things in the universe are a combination of other elements. For example water is a combination of 2 parts hydrogen and 1 part oxygen. When iron mixes with oxygen in the air it gets rusted.

### 02 what are elements

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22-Sep-08

There are only 102 known elements as we know of today in the universe. Everything else in the universe is a combination of these elements. For example iron is an element and so is gold. Hydrogen and Oxygen are also basic elements.

### 28 What is a "combination" reaction?

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22-Sep-08

Replacement Chemical Reaction: Molecules instead of joining or decomposing simply get rearranged changing partners like in a dance.

### 30 What is a "replacement" reaction?

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22-Sep-08

Combination Chemical Reaction: Smaller molecules join together to become a larger molecule like hydrogen and oxygen coming together to become water.

### 26 What is a "decomposition" reaction?

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22-Sep-08

Decomposition Chemical Reaction: A large molecule gets broken down into smaller molecules or atoms like water breaking down to become hydrogen and oxygen.

### 24 Name three types of chemical Reactions

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22-Sep-08

1. Decomposition Chemical Reaction: A large molecule gets broken down into smaller molecules or atoms like water breaking down to become hydrogen and oxygen.

2. Combination Chemical Reaction: Smaller molecules join together to become a larger molecule like hydrogen and oxygen coming together to become water.

3. Replacement Chemical Reaction: Molecules instead of joining or decomposing simply get rearranged changing partners like in a dance.

### 22 How do you test for acids or bases?

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22-Sep-08

You can use and identification paper strip. When this strip is dipped in acid it will turn red. It will turn purple for a base.

### 20 What are acids and bases?

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22-Sep-08

Liquids or solutions like lemon juice and vinegar are called acids.

Cleaning liquids like bleach and ammonia are called bases.

Liquids like water are considered neighther acids nor bases but neutral.

acids and bases react with each other chemically a lot and so one has to be very careful mixing them.

### 18 What is Rubber?

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22-Sep-08

Rubber is extracted from trees in nature. This rubber is further treated by heating it with "sulphur" to make it hard and durable. This process is called "vulcanization". Vulcanization is invented by a scientist named "Goodyear". This rubber is then used to make tires which are essential for transportation.

### 16 What is Petroleum?

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22-Sep-08

Petroleum is a kind of "oil" that is extracted from ground where it formed over millions of years from dead trees and other organic material.

When petroleum is refined and broken down we get Gasolene, Kerosene, and Diesel.

Petroleum is an essential fuel used in cars and other vehicles and also used to heat homes in winter.

### 14 What are plastics?

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22-Sep-08

Plastics are a kind of polymers. These are ligh weight and also strong and durable at the same time.

### 12 What is a Polymer?

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22-Sep-08

Materials like Nylon and Plastic are called Polymers. Polymers have their molecular structure arranged into long connecting chains like a long train with attached trailers. This chaining gives them their strength.

The "Poly" in polymer stands for "many" implying the many connections that are there between its molecular or atomic structures.

Carbon is an important element of polymers.

### 10 What is Nylon?

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22-Sep-08

Nylon is a man made replacement material for silk. Like silk it is smooth, light yet strong and durable. Carbon is an important element of Nylon. There are other man made materials like Nylon. Plastics are another example. These materials are called Polymers. Polymers have their molecular structure arranged into long connecting chains like a long train with attached trailers. This chaining gives them their strength.

Nylon is used for stockings, ropes, and nets.

### 08 What are Vitamins?

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22-Sep-08

Vitamins are chemicals in food that help the human body to be healthy and prevent some diseases.

### 06 What are antibiotics?

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22-Sep-08

Antibiotics are chemicals or medicine that cure infections by killing bacteria that cause those infections. Penicillin is an example of antibiotics.