Types of materials Around Us for class 3 science - Orchids
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Types of Materials around Us for Class 3 Science

  • Different kinds of objects surround us. These objects are either derived from nature or are made by humans.
  • Food that we eat is derived either from plants or animals.
  • Different materials are used to make various objects we use in everyday life based on their properties. For example, A shoe is made using leather, and utensils are made of plastic, Teflon, etc.
  • Some natural materials can be used directly without any processing, whereas some need to be processed before use, for example, crude oil.
natural and manmade resources

Natural Materials

Question 1:

What Is Bamboo Used for? Why It Is a Very Useful Natural Material?

Answer:

  • Bamboo is a flexible biodegradable material.
  • It is not affected by water like other wood. It does not swell up due to the absorption of water. It makes an excellent alternative to plastic as it is long-lasting and durable.
  • It is used as a raw material for construction, textiles, roads and buildings, and solid fuel.
what is bamboo used for

Question 2:

How Are Salts Derived From Nature?

Answer:

  • Salt is either derived from seawater or rocks.
  • The table salt we use at our homes is separated from seawater by evaporation, which is then purified.
  • Rock salt we use is derived from rocks and purified before use.
sources of salt

Question 3:

Animals and Plants Are Living Organisms. What Happens to the Body of Living Organisms After Their Death?

Answer:

  • Plants and animals decompose into simple nutrients after their death.
  • Decomposers act on the complex nutrients stored in animal and plant bodies while they are alive and convert them into simple nutrients that later get mixed up with the soil and are reused by new plants.
  • This process ensures the continuous formation of organic material in the soil.
Life cycle of an organism

Question 4:

Why Is Coconut Coir an Excellent Material for Making Ropes or Fishnets?

Answer:

Coconut coir is an excellent material for making ropes or fish nets due to following reasons:

  • It is cheap and can be easily extracted from the coconut fruit.
  • The fibres of coconut coir are strong, sturdy, and cannot be broken easily.
  • Coconut coir does not decompose quickly in the water, so the ropes or nets made up of coconut coir remain intact for a longer time
coconut coir as raw material

Synthetic Materials

Question 1:

Why Is Tar Used in Making the Roads?

Tar which is made using crude oil, is used for making roads due to the following reasons:

Answer:

  • Vehicles do not skid on the tar-coated surface.
  • It does not get washed away by rainwater.
  • Snow quickly melts on the tar-covered surface.
tar used for making roads

Question 2:

Electric Wires Are Made Up of Metals and Are Covered by Plastic. Why?

Answer:

  • Electric wires are made of metals as they are good conductors of electricity.
  • The plastic coating on the surface of electric wires acts as an insulator. It is done to avoid electric shocks if someone accidentally contacts the electrical wire.
metals are used to make wires

Question 3:

Why Are Safety Helmets Made Using Certain Forms of Plastics?

Answer:

Certain types of plastic are used to make helmets due to the following reasons:

  • Plastic is cheap, and light weighed.
  • It can be moulded easily.
  • It does not break easily. The thermosetting plastics do not get affected even with normal heat or fire. They require very intense heat to be melted.
uses of plastic

Properties of Materials

Question 1:

How Will You Separate Solids (Dirt or Salt) From the Liquid (Water)?

Answer:

The following methods can be used to separate dirt or salt from water:

  • Salt can be separated from water by the process of evaporation.
  • Dirt can be separated by the process of sedimentation (settling of dirt particles at the base of the container) and decantation.
  • Alum can be mixed with water to increase the rate of sedimentation and separate clear water.

Question 2:

Glass Is Fragile but Still Used to Make Windows on a Large Scale. Why Do You Think So?

Answer:

Glass is used to make windows due to following reasons:

  • It is cheaper than other materials.
  • It is transparent and allows light to pass through it.
  • It is convenient to clean the glass.
properties of materials

Question 3:

Switches in the Electric Boards Are Made of Plastic Instead of Wood. Why?

Answer:

Though both wood and plastic are insulators, plastic is used to make electric switches due to the following reasons:

  • Plastic is more durable than wood.
  • It can be heated and moulded into different shapes, unlike wood.
  • Thermosetting plastic used to make switches do not catch fire easily.
  • Plastic does not absorb water.
thermosetting plastic
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