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Grade 10Mechanics

Explain why two glass plates with a thin film of water between them are difficult to separate by a direct pull but can easily be separated by sliding.

Profile image of Hrishant Goswami
11 Years agoGrade 10
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1 Answer

Profile image of Jitender Pal
11 Years ago
There is adhesive force acting between the water molecules and the molecules present in the glass. It is much larger than the cohesive force acting between the water molecules. Due to this, a large amount of force is needed to separate the glass together. So, it is difficult to separate the glass plates by direct pull.
By sliding the glass plates, the cohesive force acting between the water molecules becomes greater than the adhesive force. Thus, there is much lower force needed to separate the glass plates. So, glass plates can be easily separated by sliding.