What is the pressure difference?

In summary, the conversation discusses the concept of gas pressure and which gas would have a higher pressure in a static system. The speaker provides a formula to support their answer, but the teacher has given a different answer without explanation. The group suggests openly discussing with the teacher, but the speaker believes it may be better to privately give their work to the teacher. Another member suggests challenging the teacher in class to expose the misunderstanding.
  • #1
Tomy World
15
5
Thread moved from the technical forums to the schoolwork forums
TL;DR Summary: Which gas has a higher pressure and why? School has provided answer which I disagree. Like to hear comment from others.

p2a.jpg
 
Physics news on Phys.org
  • #2
Welcome to PF.

If the system is static, then gas A has the higher pressure as it pushes the mercury towards the other gas B.
What do you think?
 
  • Like
Likes Tomy World
  • #3
Baluncore said:
Welcome to PF.

If the system is static, then gas A has the higher pressure as it pushes the mercury towards the other gas B.
What do you think?
Yah. It's quite straight forward, right?

My answer is
PA + ρgH1 = PB + ρgH2
PA = PB + ρg(H2-H1)

Since H2>H1, therefore PA > PB.

But teacher wrote the other way round, saying that PB is higher without given more explanation. And students hesitate to challenge teacher... I'd encourage them to openly discuss with teacher ;)
 
  • Like
Likes vanhees71
  • #4
Tomy World said:
And students hesitate to challenge teacher... I'd encourage them to openly discuss with teacher ;)
When you think a teacher gets it wrong, if you want good marks, do NOT challenge the teacher in front of the class. Give a copy of your work to the teacher after the class. Either you or the teacher will be wrong, neither of you needs public embarrassment or loss of face.
 
  • Like
  • Haha
Likes MatinSAR, phinds, Vanadium 50 and 2 others
  • #5
Baluncore said:
When you think a teacher gets it wrong, if you want good marks, do NOT challenge the teacher in front of the class. Give a copy of your work to the teacher after the class. Either you or the teacher will be wrong, neither of you needs public embarrassment or loss of face.
May be 'challenge' is a strong word. I don't mean that ;)
 
  • Like
Likes vanhees71 and Baluncore
  • #6
Your teacher should be ashamed. Ask if the teacher is sure of the result?
 
  • Like
Likes MatinSAR and vanhees71
  • #7
With an error this egregious and a resolution that is relatively straightforward to work out, my inclination would be to challenge the teacher in class. The misunderstanding needs to be exposed, rather than swept under the carpet.

The one time I had a similar disagreement (I was correct, TA was in error), I wound up being disagreed with by the TA and berated by the rest of the class. I shut up so that we could get on with the rest of the subject matter. No big deal. I knew I was right. I knew the TA was wrong and I had a good idea why. I didn't need the grade or the peer approval. I was in school to learn, not to obtain a credential or to garner the respect of others.

At the beginning of our next session, the TA had the good grace to apologize in front of the class and provide the explanation of error that I had anticipated.
 
Last edited:
  • Like
Likes MatinSAR, vanhees71, Lnewqban and 1 other person
  • #8
jbriggs444 said:
With an error this egregious and a resolution that is relatively straightforward to work out, my inclination would be to challenge the teacher in class.
I agree. Any teacher who is offended by a POLITE challenge doesn't belong there.
 
  • Like
Likes vanhees71 and weirdoguy

What is the pressure difference?

The pressure difference is the difference in pressure between two points in a fluid or gas. It is typically measured in units of force per unit area, such as pounds per square inch (psi) or pascals (Pa).

How is pressure difference calculated?

Pressure difference is calculated by subtracting the pressure at one point from the pressure at another point. This can be done using a pressure gauge or by using mathematical equations, such as Bernoulli's equation.

What causes pressure difference?

Pressure difference is caused by a variety of factors, including changes in elevation, temperature, and velocity. It can also be created by external forces, such as air flow or compression.

Why is pressure difference important?

Pressure difference is important in many scientific and engineering applications. It helps us understand fluid and gas behavior, such as in weather patterns and aerodynamics. It is also crucial in designing and maintaining systems that rely on pressure differentials, such as pipelines and ventilation systems.

How can pressure difference be measured?

Pressure difference can be measured using various instruments, such as manometers, pressure gauges, and barometers. These instruments typically rely on the displacement or deformation of a fluid or material to determine the pressure difference. Advanced techniques, such as laser interferometry, can also be used to measure pressure differences with high precision.

Similar threads

  • Introductory Physics Homework Help
Replies
15
Views
441
  • Introductory Physics Homework Help
Replies
5
Views
583
Replies
207
Views
3K
  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
411
  • Introductory Physics Homework Help
Replies
6
Views
810
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
24
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
493
  • Introductory Physics Homework Help
Replies
3
Views
765
Back
Top