How Do SI Units Affect Calculations in Fluid Statics?

  • #1
clueless8
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Homework Statement
I'm having trouble getting the correct answer on two problems within one and I don't know where I'm going wrong. I will go to my T.As during the week but I would rather finish my homework this weekend.

The question is If you were to dive down 12.5m below surface level, what is
1. The pressure due to water alone?
2.The total or absolute pressure at depth given atmospheric pressure = 1.01E5 N/m^2
Relevant Equations
P = hpg
Ptotal = Pgauge + Patm
For A) I used P = hpg (h=0.0125km, p=1000kg/m^3, and g= 9.8m/s^2) this gave me 122.5N/m^2
For B) I used Ptotal = Pgauge + Patm
= 1.01E5 + 122.5 = 101122.5 N/m^2
 
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  • #2
clueless8 said:
Homework Statement: I'm having trouble getting the correct answer on two problems within one and I don't know where I'm going wrong. I will go to my T.As during the week but I would rather finish my homework this weekend.

The question is If you were to dive down 12.5m below surface level, what is
1. The pressure due to water alone?
2.The total or absolute pressure at depth given atmospheric pressure = 1.01E5 N/m^2
Relevant Equations: P = hpg
Ptotal = Pgauge + Patm

For A) I used P = hpg (h=0.0125km, p=1000kg/m^3, and g= 9.8m/s^2) this gave me 122.5N/m^2
For B) I used Ptotal = Pgauge + Patm
= 1.01E5 + 122.5 = 101122.5 N/m^2
Why did you convert to km?
 
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  • #3
Welcome!

1 Pascal = Force of 1 Newton per square meter
Atmospheric pressure at sea level = 101,325 Pascals = 760 mm Hg = 760 torr = 14.7 psi = 1 atm
 
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  • #4
Lnewqban said:
Welcome!

1 Pascal = Force of 1 Newton per square meter
Atmospheric pressure at sea level = 101,325 Pascals = 760 mm Hg = 760 torr = 14.7 psi = 1 atm
The valuel of atmospheric pressure to use is given.
 
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  • #5
clueless8 said:
For A) I used P = hpg (h=0.0125km, p=1000kg/m^3, and g= 9.8m/s^2) this gave me 122.5N/m^2
Check your units!
 
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  • #6
haruspex said:
Why did you convert to km?
I have trouble in this area, I assumed I had to due because the final answer asks for N/m^2 so I thought it had to be in km due to SI units , should I stick with 12.5m ?
 
  • #7
clueless8 said:
I have trouble in this area, I assumed I had to due because the final answer asks for N/m^2 so I thought it had to be in km due to SI units , should I stick with 12.5m ?
The SI base unit of length is 1 m, not 1 km. The derived unit of newton is 1 N = 1 kg m/s2, not a km to be seen anywhere. The only ”k” in there is in kg, the SI base unit for mass.
 

FAQ: How Do SI Units Affect Calculations in Fluid Statics?

1. What are SI units and why are they important in fluid statics calculations?

SI units, or the International System of Units, are a standardized system of measurement used globally in scientific and engineering calculations. In fluid statics, they provide a consistent framework for measuring and calculating properties like pressure, density, and volume, ensuring that results are accurate and comparable across different studies and applications.

2. How does using SI units simplify calculations in fluid statics?

Using SI units simplifies calculations in fluid statics by eliminating the need for unit conversions. Since all measurements are in a standard format, equations can be applied directly without adjusting for different unit systems. This reduces the risk of errors and makes the computational process more straightforward.

3. What are the common SI units used in fluid statics and their corresponding quantities?

In fluid statics, the common SI units include the pascal (Pa) for pressure, the kilogram per cubic meter (kg/m³) for density, the meter (m) for length, and the cubic meter (m³) for volume. These units are used to describe the properties and behavior of fluids at rest.

4. How do SI units affect the interpretation of fluid statics equations?

SI units affect the interpretation of fluid statics equations by providing a clear and consistent basis for understanding the relationships between different physical quantities. For example, the hydrostatic pressure equation, P = ρgh, where P is pressure, ρ is density, g is the acceleration due to gravity, and h is height, relies on SI units to ensure that the calculated pressure is in pascals (Pa).

5. Can using non-SI units lead to errors in fluid statics calculations?

Yes, using non-SI units can lead to errors in fluid statics calculations due to the potential for incorrect unit conversions and inconsistencies. Non-SI units may require additional steps to convert measurements into a common system, increasing the risk of mistakes and complicating the computational process. Sticking to SI units helps maintain precision and clarity in calculations.

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