• Bolter
In summary, the manometer reading for part b) is the height difference between the level A and new level of the surface of mercury, which is 51.76mm.
Bolter
Homework Statement
See below
Relevant Equations
pressure = density * g * h
Having some trouble in answering part b) of this question

I managed to find the right answers for part a) if that is maybe needed in part b) which I got 26.7 kPa, 18.8 kPa, 38.6 kPa and 13.9 kPa for levels A, B, C and air pressure respectively

Not too sure what part b) is technically asking but I redrew the diagram and made the adjustment on the right side from what the question was asking

Would the new manometer reading be '0.2 x sin15 = 0.0576m as we're only concerned with the vertical change in height that affects pressure?

Any help would be appreciated! Thanks

The level of the surface of mercury does not change because the pipe gets inclined, but it requires more mass inside the tube.
The inclination of one tube an its scale is common practice to be able to see very small variations of level, that would be difficult to spot in a vertical tube.
If you were not adding some mercury into the bent tube, you would be altering the balance previously achieved in a).

Last edited:
Lnewqban said:
The level of the surface of mercury does not change because the pipe gets inclined, but it requires more mass inside the tube.
The inclination of one tube an its scale is common practice to be able to see very small variations of level, that would be difficult to spot in a vertical tube.
If you were not adding some mercury into the bent tube, you would be altering the balance previously achieved in a).

I see. For the new manometer reading that it asks for, I only need to find the height difference between level A and new level of the surface of mercury. That gives me h = 0.2 * sin15 = 0.05176m = 51.76mm

But this is wrong as the correct answer is in fact 773mm which it says from the sheet.

Perhaps if you consider 773 mm to be the hypotenuse of the triangle formed by height 200 mm and the angle?

Again, to keep balance of the system (same pressures and heights), the imaginary vertical column of mercury must remain being 200 mm.

Bolter
Lnewqban said:
Perhaps if you consider 773 mm to be the hypotenuse of the triangle formed by height 200 mm and the angle?

Again, to keep balance of the system (same pressures and heights), the imaginary vertical column of mercury must remain being 200 mm.

Thanks I kept the imaginary vertical mercury column to remain as 200mm, and I managed to calculate 773mm in the end using basic trig. I got what the extra mercury mass needed to be too

Lnewqban
You are welcome

## 1. What is a manometer reading?

A manometer reading is a measurement of the pressure difference between two points in a fluid system. It is typically used to measure the pressure of gases or liquids.

## 2. How is the manometer reading calculated?

The manometer reading is calculated by subtracting the pressure at one point in the system from the pressure at another point. This difference in pressure is typically measured in units of inches of water column (inH2O) or millimeters of mercury (mmHg).

## 3. What equipment is needed to calculate the manometer reading?

To calculate the manometer reading, you will need a manometer, a fluid (such as water or mercury), and a way to measure the height of the fluid column (such as a ruler or measuring tape).

## 4. What are some common uses of manometer readings?

Manometer readings are commonly used in HVAC systems, to measure the pressure of gases in industrial processes, and in laboratory experiments to measure the pressure of gases or liquids.

## 5. What factors can affect the accuracy of manometer readings?

The accuracy of manometer readings can be affected by factors such as changes in temperature, changes in the density of the fluid being measured, and air bubbles or other impurities in the fluid. It is important to carefully calibrate and maintain the manometer to ensure accurate readings.

• Introductory Physics Homework Help
Replies
12
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
2K
• Introductory Physics Homework Help
Replies
23
Views
3K
• Introductory Physics Homework Help
Replies
4
Views
27K
• Other Physics Topics
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Engineering and Comp Sci Homework Help
Replies
6
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
6K
• Introductory Physics Homework Help
Replies
6
Views
10K
• Mechanical Engineering
Replies
4
Views
6K