18. Rishi placed a straw inside a beaker of water. He then closed the top of the straw with a finger and removed the straw from water. What did he observe and why?
Answers
Answer:
According to the question,he(Rishi) observed some amount of water after removing the straw from the beaker the water is stored inside the straw until he removes his finger from the top of the straw
The observation is due to a few basic phenomenon. The first is capillary action, vacuum and the second is pressure. The liquid enters the straw because as you suck into the straw, a vacuum is created inside it. The liquid then enters due to capillary action. It demonstrates the forces between the molecules of the liquid. The air molecules in the atmosphere exert pressure onto the molecules of the liquid. Closing the top of the straw with the finger prevents the air from entering into it. So, there is no downward force on the liquid. The air pressure is exerted only from the upward direction which is stronger and therefore, the liquid stays inside the straw.