Question

Take a glass full of water (fig.A) and put a piece of thick card on it. Now turn the glass upside down as shown in fig.B what will happen?

A) The card will not fall
B) The card will fall down
C) Water will leak through the sides
D) None of the above

Answer 1

Hint: In the above-mentioned question we have to first analyze the given situation, in which we will get what forces are acting. Upon the illustration, we will see that the basic phenomenons acting on the situation are the atmospheric pressure ( pressure exerted by the air around over a system), and the other one is the force of adhesion ( the binding force of physicality). Then we can notice that the card won’t feel when both of them act simultaneously.

Complete step by step answer:
In this question, there are various reasons and phenomena that govern the result.
First, there is the phenomenon of the ‘Atmospheric Pressure’. The pressure exerted by the surrounding atmosphere on the given system is the atmospheric pressure.
According to it the weight of the water and the card is being countered by the force that has been exerted by the presence of the air on the card at the bottom of the system.
Now the other reason for this result is the phenomenon of ‘Adhesion’.
Specifically, here we are talking about the adhesion power of the water molecules which is exerted on the cardboard and the glass.
This phenomenon takes place because the water molecules consist of two ends, one positive and another negative. This polarity leads to the attraction strength to the other materials too.
In the above-concluded experiment, the water molecules are attracted to the paper. This leads to the adhering to it. This happens while continuing the surface tension with the other water molecules.

$\therefore$ The right answer is option A, that the card will not fall.

Note:
In the process of the adhesion, the dissimilar particles stick together. It is similar to cohesion. In the case of similar particles, this effect is called cohesion whereas for the dissimilar particles it is adhesion. Adhesion results from the physical properties of the interface between two phases.