Pressure in Closed Tank | Is the Author Wrong?

In summary: If the cap were airtight, then the pressure would be at atmospheric pressure inside the tank.Sure. It might start out at P atm at the moment a seal was made though.
  • #1
foo9008
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4

Homework Statement


in this question , the author stated that the P1 = P atm , but at point 1 , the gas tank is not open to the atmosphere, it is a closed tank . so , is the author wrong ? again , at point 2 , the tank isn't open to atmosphere, why it is P2= P atm ?

Homework Equations

The Attempt at a Solution

 

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  • #2
Why might the two pressures be P atm? Can you think of any reason? How does the small diameter hose reach the liquids?
 
  • #3
gneill said:
Why might the two pressures be P atm? Can you think of any reason? How does the small diameter hose reach the liquids?
i don't think P1 and P2 = P atm ...
 
  • #4
foo9008 said:
i don't think P1 and P2 = P atm ...
I understand that. But can you think of any way that they could?
 
  • #5
gneill said:
I understand that. But can you think of any way that they could?
for P1 = P2 = P atm , the tank is not closed?
 
  • #6
foo9008 said:
for P1 = P2 = P atm , the tank is not closed?
Correct. How does the hose enter each tank?

upload_2016-4-8_10-59-47.png
 
  • #7
gneill said:
Correct. How does the hose enter each tank?

View attachment 98796
at point 1 , it is immersed in the gas tank , while the point 2 is at the hole only , not completely immersed . What are you trying to tell ?
 
  • #8
foo9008 said:
at point 1 , it is immersed in the gas tank , while the point 2 is at the hole only , not completely immersed . What are you trying to tell ?
I'm pointing out that neither tank is sealed. Both are open to the atmosphere through their filling apertures. The siphon hose does not make an air-tight seal at either opening.
 
  • #9
gneill said:
I'm pointing out that neither tank is sealed. Both are open to the atmosphere through their filling apertures. The siphon hose does not make an air-tight seal at either opening.
if that is air-tight selaed , then the pressure acting would not be P atm anymore , am i right ?
 
  • #10
foo9008 said:
if that is air-tight selaed , then the pressure acting would not be P atm anymore , am i right ?
Sure. It might start out at P atm at the moment a seal was made though.

But there is no seal mentioned in the problem statement. The assumption is that, as in the real-life situation for siphoning gas in this manner, the hose fits loosely through the gas cap opening and down into the liquid.
 

Related to Pressure in Closed Tank | Is the Author Wrong?

1. What is pressure in a closed tank?

Pressure in a closed tank refers to the force exerted by the gas or liquid inside the tank on the walls of the container. It is measured in units of force per unit area, such as pounds per square inch or pascals.

2. How is pressure in a closed tank calculated?

The pressure in a closed tank can be calculated using the ideal gas law, which states that pressure is equal to the number of moles of gas multiplied by the gas constant and the temperature, divided by the volume of the tank. Alternatively, it can also be measured using a pressure gauge.

3. What factors affect pressure in a closed tank?

The pressure in a closed tank can be affected by several factors, including the temperature of the gas or liquid inside, the volume of the tank, and the number of moles of gas present. Changing any of these factors can alter the pressure inside the tank.

4. Can pressure in a closed tank ever exceed the maximum limit?

Yes, pressure in a closed tank can exceed the maximum limit if the temperature or number of moles of gas inside the tank increases significantly. This can lead to a dangerous buildup of pressure, causing the tank to rupture or explode.

5. Is the author wrong about pressure in a closed tank?

Without more context, it is impossible to determine if the author is wrong about pressure in a closed tank. However, it is important to always double check information from reliable sources and use equations and formulas accurately to ensure accurate results and understanding of pressure in closed tanks.

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