Question

Сравнительно легко перемещается сухое стекло по сухому стеклу. Легче или труднее перемещать стёкла друг относительно друга, если их слегка смочить? ПОЧЕМУ?

Answer 1

У сухих стекол молекулы взаимодействуют слабо, потому что расстояние между ближайшими молекулами этих стекол намного больше, чем расстояние между молекулами самих стекол, которые друг друга притягивают, стараются "не пускать". Если эти стекла смочить, то между далекими молекулами двух стекол возникают молекулы воды, которые своими взаимопритяжениями как бы создать связи между ними. Вот эти дополнительные межмолекулярные силы  притяжения со стороны молекул воды  и мешают перемещению стекол.
 

Answer 2

Comparing the Movement of Dry Glass vs. Slightly Wet Glass

When comparing the movement of dry glass against slightly wet glass, it is generally easier to move dry glass on dry glass. This is because the dry surfaces create less friction, allowing for smoother movement. However, when the glass surfaces are slightly wet, the presence of moisture can increase the friction between the two surfaces, making it more difficult to move the glasses relative to each other.

The presence of moisture on the glass surfaces creates a thin layer of water molecules, which can act as a lubricant. While this lubrication can reduce friction to some extent, it can also create adhesion between the two surfaces, making them stick together. This adhesion can make it harder to initiate movement and require more force to overcome.

Additionally, the movement of wet glass on wet glass can be further affected by factors such as the amount of moisture present, the smoothness of the glass surfaces, and the pressure applied. These factors can influence the overall ease or difficulty of moving the glasses relative to each other.

In summary, while dry glass on dry glass generally offers easier movement due to reduced friction, the presence of moisture on the glass surfaces can increase friction and create adhesion, making it more challenging to move wet glass on wet glass.

Note: The information provided above is based on general observations and principles of physics. The specific ease or difficulty of moving glass on glass can vary depending on various factors, including the condition of the glass surfaces and the presence of any additional substances or contaminants.