Question

You are provided with two surfaces-- rough and smooth.Which will it be easier to press a rubber sticker on? Give reasons

Answer 1

A rubber sticker creates a vacuum between the rubber cap and the surface. Due to atmospheric pressure, the rubber sticker sticks to the surface. Now, on a rough surface, vacuum can not be created, since all the air between the cup and the surface does not escape. The remaining air between the cup and the rough surface exert pressure on the inner wall of the cup, thus it does not stick on the rough surface. On the other hand, it's entirely the opposite in case of a smooth surface, which makes it an ideal surface for the rubber sticker to stick.