CANDLE IN A GLASS
Can we lift a candle without using our hands but only the laws of physics? By pressing the glass over the candle, we prevent air from entering the glass so the oxygen is not renewed. The flame is extinguished after all the available oxygen in the glass has been burned off. Because of the air inside the glass cools down sharply after the candle is extinguished and the air pressure is also reduced. Thus, the pressure inside the glass is lower than the pressure outside of the glass (atmospheric pressure). Liquids always move towards the lower pressure so water is accumulated inside the glass.