Why the all statements are true and D option is correct as in the absence of air windmills produce electricity and in the absence of air birds and insects fly so, why?
Solution
It is the air movement which helps in flying of birds and insects and also flying of aeroplanes sailing of yacht as well as movement of wind mills.
Air moment is always present around us. When air moves very fast it is known as wind.
However if there is a hypothetical situation in which air is completely absent then the windmills , insects, birds etc will not be able to move.
This is because, insects and birds flap their wings which thereby propels the air around and they can therefore move.
Similarly airplanes have a streamlined structure and even yachts are built in manner that they can propel the air around and move or fly.
If air will be absent, they all can't move or fly. Hence, all the given options are correct.
It is the air movement which helps in flying of birds and insects and also flying of aeroplanes sailing of yacht as well as movement of wind mills.
Air moment is always present around us. When air moves very fast it is known as wind.
However if there is a hypothetical situation in which air is completely absent then the windmills , insects, birds etc will not be able to move.
This is because, insects and birds flap their wings which thereby propels the air around and they can therefore move.
Similarly airplanes have a streamlined structure and even yachts are built in manner that they can propel the air around and move or fly.
If air will be absent, they all can't move or fly. Hence, all the given options are correct.