Question

a hydraulic is designed with a line that is 18 ft long. if the applied pressure at one end of the line is 92 pa, what is the applied pressure at the other end?
pa
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1. -/1.91 points

why is it when you blow over a piece of paper it rises?
when you blow over the top of the paper it becomes gravitationally repulsive and hence it rises.
when you blow over the top of the paper you increase the buoyancy of the paper and as a result it rises.
the air above the paper is moving while the air below the paper isnt moving. thus, the pressure above the paper is lower than the pressure below the paper. hence, the paper rises.
when you blow over the top of the paper the paper becomes charged and rises much in the same way that the hair on a persons head rises when it becomes charged.
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Explanation:

First Problem (Hydraulic Pressure)

Step1: Recall Pascal's Law

Pascal's Law states that in a fluid at rest in a closed container, a pressure change in one part is transmitted without loss to every portion of the fluid and the walls of the container. So, the pressure at the other end should be the same as the applied pressure at one end.

Step2: Determine the pressure

Given the applied pressure at one end is 92 Pa. By Pascal's Law, the pressure at the other end is also 92 Pa.

• The first option is wrong as gravity isn't repulsive here.
• The second option is wrong as buoyancy isn't the reason (buoyancy relates to fluid displacement, not air speed).
• The third option is correct: Blowing over the paper increases air speed above it. By Bernoulli's principle, higher speed means lower pressure. The air below the paper has higher (atmospheric) pressure, so the pressure difference lifts the paper.
• The fourth option is wrong as the paper doesn't get charged in this process.

Answer:

92

Second Problem (Paper Rising Explanation)