1. Explain why wood cannot be used to make cooking utensils? 2. How do woollen clothes keep us warm in winters? 3. What is meant by insulators? 4. Explain the term brittle and malleable. 5. What makes metal dull after some time? 6. Why do we classify materials?
Answer (1)
Explain why wood cannot be used to make cooking utensils?
Wood is generally not used to make cooking utensils that come into direct contact with heat for several reasons. Firstly, wood is a flammable material, which means it can catch fire easily when exposed to high temperatures. This poses a safety hazard. Secondly, wood can char or crack when exposed to heat, making it unsuitable for direct cooking use.
How do woollen clothes keep us warm in winters?
Woollen clothes keep us warm in winter because wool is an excellent insulator. Wool fibres trap air between them, creating an insulating layer that helps prevent the loss of body heat. This trapped air layer minimizes heat transfer, keeping warmth close to the body, and thus, maintaining a comfortable temperature even in cold conditions.
What is meant by insulators?
Insulators are materials that do not allow heat or electricity to pass through them easily. They are used to prevent the transfer of heat or electricity from one area to another. Common examples of insulators include rubber, plastic, and glass, which are often used to coat electrical wires or in objects to provide thermal insulation.
Explain the term brittle and malleable.
Brittle: A material is considered brittle if it breaks or shatters easily when subjected to stress or force without significant deformation. Common examples of brittle materials are glass and ceramics.
Malleable: A material is malleable if it can be hammered or rolled into thin sheets without breaking. Metals like gold, silver, and copper are highly malleable, making them ideal for shaping into different forms for various applications.
What makes metal dull after some time?
Metals become dull over time due to a process called oxidation, which is a chemical reaction with oxygen in the air. This reaction forms a thin layer of oxide on the metal's surface, often resulting in a dull appearance. For example, iron forms iron oxide, also known as rust, while silver develops a tarnish.
Why do we classify materials?
We classify materials to better understand and organize the properties and uses of different substances. Classification helps in identifying materials for specific applications, facilitates communication and education, and aids in scientific research and development. By grouping materials based on similarities and differences, it becomes easier to study their properties and how they can be used effectively.
