Out of those,
wood, rock, minerals, water are natural. Human performed research on various natural
materials in laboratory. With the help of it, various materials are manufactured in factories.
Such materials are called as manmade materials. eg. Glass, plastic, artificial threads,
thermocol, etc explain in brief
Answers
Answer:
Explanation:
Thermocol is a form of a complex material called polystyrene. It transforms into a liquid state on heating at more than 100 ºC temperature and returns to solid state on cooling. Due to this, we can give any desired shape to it. Being a good shock-absorber, it is used in packing of delicate items.
Answer b: Polyvinyl chloride (PVC) is a plastic polymer made of monomer vinyl chloride. PVC are used for manufacturing toys, combs, plates, bowls etc.
Explanation:
Friction is a force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor, friction makes this difficult. Friction always works in the direction opposite to the direction in which the object is moving, or trying to move.