Suppose you have a very long straw that can reach from a cup of water on the ground level to the top of a
very tall building. When you use a pump to suck on the straw in order to bring water up,
a. you can bring the water up to any height with no problem.
b. you can bring the water up to only a maximum height in the straw, when the pressure of
the water column is approximately equal to the atmospheric pressure.
c. you can bring the water up to only a certain height in the straw, because after it will flash
freeze in the cup.
d. you cannot bring the water up by more than a few inches.
vacuum doesn't pull, pressure pushes
b.
To determine the correct answer, let's analyze the concepts of pressure and atmospheric pressure.
When you use a pump to suck on the straw, you create a pressure difference, with lower pressure inside the straw compared to the atmospheric pressure outside. This pressure difference allows you to bring the water up the straw.
Now, let's evaluate each option:
a. "You can bring the water up to any height with no problem": This is not likely to be true. As you suck on the straw, the pressure inside decreases, causing the water to rise. However, there is a limit to how high the water can be lifted because of atmospheric pressure.
b. "You can bring the water up to only a maximum height in the straw when the pressure of the water column is approximately equal to the atmospheric pressure": This is the most accurate option. The maximum height the water can be lifted is determined by the balance between the pressure inside the straw and the atmospheric pressure. Once the pressure inside the column of water in the straw is equal to the atmospheric pressure, the water will stop rising.
c. "You can bring the water up to only a certain height in the straw because after it will flash freeze in the cup": Flash freezing is not directly related to the height the water can be brought up in the straw. It depends on various factors like temperature, but it does not limit the height the water can be lifted.
d. "You cannot bring the water up by more than a few inches": This is an incorrect option. As explained before, the height the water can be brought up is determined by the balance between the pressure inside the straw and the atmospheric pressure, not a limitation of a few inches.
Considering the explanations provided, the correct answer is option b: You can bring the water up to only a maximum height in the straw, when the pressure of the water column is approximately equal to the atmospheric pressure.