مواد و خواص آنها

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النص الكامل للفيديو

you use objects every single day but have you ever thought about what they are made of why are some bendy and some are really hard wire some smooth and shiny and some bumpy and rough when it comes to the objects around us they can be very different from one another can you think of some materials you see in the classroom or at home you might have come up with materials like glass wood plastic metal paper fabrics or rubber do you know what the properties of some of these materials are you might know that wood is hard plastic is waterproof fabrics and rubber are flexible metal is strong and resistant do you know how some of these are used and why they are chosen to make objects with objects are made from materials that are specially chosen depending on the purpose this is because materials have special properties that help them do their job take this umbrella for example the handle is made from hard materials while the umbrella shield is often made from plastic the hard materials were used for the handle because it is strong and perfect for supporting the top of the umbrella and the plastic was chosen because it is waterproof and light which lets the rain drip off while allowing you to carry it easily why do you think we use glass for windows and reading glasses you've probably already guessed it because you can see through it these objects wouldn't be much use if they were made of wood would they you may have noticed by now that our clothes are made out of special materials as well and these materials also have unique properties can you guess what materials your clothes are made of they might be cotton which is fabric that helps you stay cool on hot day or they might be made from wool which is very good at keeping you warm on those cold winter days what do you think would happen if you wore t-shirt made from metal well that would just be silly wouldn't it you wouldn't even be able to move can you now see why we choose certain materials for our clothing they let us move easily and stay comfortable because they are flexible and help us keep warm or cool depending on the weather now which of these houses is different from the others of course it's the house made out of flimsy paper that is different have you ever seen house built from paper no way when it comes to building houses we need to use tough materials such as bricks glass wood and cement so that they stay standing for long time and don't blow over in the wind now that you know about materials and they're awesome properties wonder if you can spot some of them around your school you