Solving for Pressure Rise in Manometer with Oil & Mercury

In summary, the conversation discusses a problem involving a manometer filled with oil and connected to an air tank. The question asks how much the fluid level will rise in the open side of the manometer when the pressure in the tank increases by 0.72 cm of Hg. Two solutions are attempted but do not yield a correct answer. The final solution involves setting the pressure of the oil equal to the pressure of mercury and solving for the height of the oil column, which should be around 10 cm.
  • #1
agadag
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Homework Statement



A manometer using oil (density 0.91 g/cm3) as a fluid is connected to an air tank. Suddenly the pressure in the tank increases by 0.72 cm of Hg. (a) By how much does the fluid level rise in the side of the manometer that is open to the atmosphere? (b) What would your answer be if the manometer used mercury instead?

Homework Equations



P = rho*gravity*height

The Attempt at a Solution


I have looked at several options of solving this problem. None of them make any sense to me. Please help. Thankyou!
 
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  • #2
The question is asking how high does a column of oil have to be to weigh the same as a 0.72cm column of mercury
 
  • #3
ok.
so i set the to two pressures equal to each other
so i got P(oil)=P(mercury)
(.91)(980)h = (980)(.72)(13.6)
solved for h, and provided my answer in cm but its not right :\
 
  • #4
If I'm reaing the question in the same way as you that should be correct (you can ignore 'g' it cancels)
The oil is roughly 15x less dense than mercury - so you should have an answer around 10cm (roughly)
 
  • #5
yea i got 10.76. Its not right...
 

1. What is a manometer?

A manometer is a scientific instrument used to measure the pressure of fluids. It consists of a U-shaped tube filled with a liquid, such as mercury or oil, and is connected to the system where pressure needs to be measured.

2. How does a manometer work?

A manometer works by balancing the pressure of the fluid in the U-shaped tube with the pressure of the fluid in the system being measured. The difference in height between the two sides of the tube is proportional to the pressure difference between the two fluids.

3. How do you solve for pressure rise in a manometer?

To solve for pressure rise in a manometer, you will need to measure the height difference between the two sides of the U-shaped tube and use a formula to calculate the pressure difference. This formula takes into account the density of the liquid used in the manometer and the acceleration of gravity.

4. Why is oil sometimes used in a manometer instead of mercury?

Oil is often used in a manometer instead of mercury because it is less toxic and easier to handle. Additionally, oil does not evaporate as easily as mercury, making it a more reliable choice for long-term measurements.

5. What are the limitations of using a manometer to measure pressure?

One limitation of using a manometer is that it can only measure pressure differences between fluids, not absolute pressures. Additionally, the accuracy of the measurement can be affected by factors such as temperature and air bubbles in the liquid. Care must also be taken to ensure that the manometer is properly calibrated and that the liquid used is appropriate for the pressure range being measured.

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