Put a straw in a glass containing some water, such a little amount ofenters through the straw, then put the finger over the other end. Lift the straw up. a) What do you observe? b) Explain the phenomenon. c) If a hole is made on the upper part of the straw, what happens and why?

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Solution

a) the small amount of water sucked into the straw will stuck in the straw.

b)When you cover the hole of the straw with your thumb and take the straw out of the water, the pressure of the trapped air side inside the straw is less than the pressure of the air outside the straw: so the water is 'pushed' into the straw by the outside atmosphere.

c)if a hole is made on the upper part of the straw the pressure inside the straw increases and the water will not hold in the straw.

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Question 3

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