Explain the following observations scientifically :
(a) Huge ice blocks are covered with sawdust and packed in jute sacks
during transfer.
(b) During winters, the metallic handles of wooden doors are colder
than the doors.
(c) Deserts are cooler during nights.
(d) A bird fluffs its feather on a cold day.
(e) A black car gets hotter in the sun than a white car.
(f) A double layered blanket is warmer than a single thick blanket.
(g) The heating element of an electric kettle is at the bottom.
(h) Ventilators are provided near the roof of rooms in our houses
Answers
Answer:
ans :- a) huge ice blocks are covered with sawdust and packed in jute sacks during transfer as they do not transfer the heat of the surrounding to the ice.
ans :- b) The metallic handle of a door feels colder than the wooden door on a cold day because metallic handle is a good conductor of the heat while wooden door is a bad conductor of the heat. Therefore, in case of the metallic conductor the process of conduction takes place and it gets cold because of the cold surrounding.
ans :- c) Heat and humidity
During the day, sand's radiation of the sun's energy superheats the air and causes temperatures to soar. But, at night most of the heat in the sand quickly radiates into the air and there is no sunlight to reheat it, leaving the sand and its surroundings colder than before.
ans :- d) Air between birds body gets warm very soon . To trap some more air in cold weather it fluffs it feather so that she can keep her body warm .
ans :- e) Unfortunately for drivers who love black exterior paint, this car myth is true. Darker paint colors, especially black, will absorb more of the heat from the sun and lighter paint colors will reflect it.
ans :- f) Air is trapped in the space between two thin blankets. Since air is an insulator of heat, it prevents the escape of body heat. That is why two thin blankets are usually warmer than one thick blanket.
ans :- g) If you placed the heating element at the top and the kettle isn't full, the water wouldn't get heated because the element isn't there so you would still have cold or at most lukewarm water. ... When it's at the bottom, hot water weighs less than cold water so it rises to the top, thus heating all the way through.
ans :- h) Ventilators are provided near ceilings in the rooms of our houses because the air we breathe out is warm and rises out of the room through the ventilators. Cool fresh air rushes into the room through the doors and windows.