Question

Explain the following observation very briefly.
(a) A firki does not rotate in a closed area.​
(b) The arrow of weather cock points towards a particular direction at a particular moment.
(c) An empty glass in fact is not empty.
(d) Breathing through mouth may harm you.

Answer 1

(a)
Moving air is responsible for rotation of a firki in an open area. This moving air or wind is absent in a closed area, that is why firki does not rotate in a closed area.
(b)
The arrow of the weather cock points towards a particular direction at a particular moment because it shows the direction of the wind at a particular moment.​
(c)
An empty glass in fact is not empty as it is filled with air. Air occupies the empty space of any object in the earth's atmosphere.​
(d)
Breathing through mouth harms us because the air contains dust particles and if we breathe through mouth then the harmful dust particles may enter our body and cause damage to lungs. If we breathe through the nose, hair present inside prevents the dust particles from entering inside.​