Naturally occurring materials can be used by humans to make various objects. Justify
the statement by giving examples.
Answers
Mostly, materials do not occur as a single crystal, but in polycrystalline form, i.e., as an aggregate of small crystals with different orientations.
Explanation:
Natural resources are materials or things that people use from the earth. There are two types of natural resources. The first are renewable natural resources. They are called renewable because they can grow again or never run out. The second are called nonrenewable natural resources. These are things that can run out or be used up. They usually come from the ground.
Let's look more closely at renewable natural resources. They are the ones that can grow again. Trees are a good example. If cut down, they can regrow from seeds and sprouts. Animals are another example. Baby animals are born and grow up. They replace older animals that die.
Trees are one of the most useful renewable natural resources. We use trees to produce almost 8,000 different things, like this cardboard box. Wood is used to make most of these products. Tree wood is in our homes, furniture, paper, and on and on. Tree chemicals are also used to produce things like rayon cloth, food, medicine, and rubber.
By-products are things made out of leftovers. For example, when a tree is cut down and sawn up for wood, the leftover sawdust can be used for fuel, making particle board like in the picture, or animal bedding. These are by-products. Another by-product from harvesting trees is bark mulch for gardens.
Air and water are renewable natural resources too. They don't regrow like trees or have babies like animals. But, they are always being renewed. They move in cycles. They go from one place to another, and often back where they started, again and again. This is a good thing, because all living things need air and water to survive. There is one other type of renewable natural resource. It includes sources of power like sun and wind energy. These are never ending. Finally, remember this: renewable resources can regrow or be replaced within a person's lifespan.
Nutrients are chemicals that living things need. They are renewable natural resources. They move round and round in cycles and never run out. When an animal like this cow eats a plant, it takes in nutrients. The nutrients are used in the animal's body and then many come out as waste, which returns the nutrients to the soil. When the animal dies, nutrients will return to the soil as well. Plants take up the nutrients in the soil and continue the cycle.
Now, let's look at nonrenewable natural resources. They are found in the ground. There are fixed amounts of these resources. They are not living things, and they are sometimes hard to find. They don't regrow and they are not replaced or renewed. They include the fossil fuels we burn for energy (natural gas, coal, and oil). Minerals, used for making metals, are also nonrenewable natural resources.
Fossil fuels such as oil, coal, and gas will not last forever. They are nonrenewable. Wind, solar, and hydrogen power are renewable resources that offer hope for the future.
People use both types of natural resources to produce the things they need or want. Our homes, clothing, plastics, and foods are all made from natural resources.