Calculate discharge in L/s and Kg/s

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Discussion Overview

The discussion revolves around calculating the discharge of oil from a tank through a pipe, specifically focusing on converting the discharge rate into liters per second (L/s) and kilograms per second (Kg/s). The context includes homework-related calculations involving fluid dynamics and density considerations.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant calculates the density of the oil and the discharge rate, arriving at a mass flow rate of approximately 6.79 Kg/s.
  • Another participant clarifies that 1 L of the oil corresponds to 0.8 kg, contrasting it with water's density of 1 kg per liter.
  • A subsequent post questions whether the calculated values of Kg/s and L/s are equivalent, seeking confirmation on the results.
  • A later reply agrees with the mass flow rate but suggests rounding the numbers to two significant figures based on the precision of the given measurements.

Areas of Agreement / Disagreement

Participants generally agree on the mass flow rate calculation but there is some uncertainty regarding the conversion between L/s and Kg/s due to the specific gravity of the oil. The discussion does not reach a consensus on the final presentation of the results.

Contextual Notes

Participants note that the accuracy of the results may depend on the significant figures of the measurements provided in the problem statement.

Parsifal1
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Homework Statement


A tank contains oil with a specific gravity of 0.80, which is discharged through a 30mm diameter pipe at 12m/s. Calculate the discharge in L/s and Kg/s.

Homework Equations


specific gravity=density of oil/density of water
mass flow rate=volume flow rate*density
volume flow rate=velocity*area

The Attempt at a Solution


Density=(0.8*1000)=800 kg/m^3
Area=pi(0.015)^2=7.068583471*10^-4
Q=12*7.068583471*10^-4=8.482300165*10^-3
m=8.482300165*10^-3*800=6.785840132 kg/s

Shouldn't L/s be the same since 1L=1Kg?
 
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Shouldn't L/s be the same since 1L=1Kg?
No. 1 L = 0.8 kg for this oil. Water has a density of 1 kg per litre. (All approximate.)
 
Merlin3189 said:
No. 1 L = 0.8 kg for this oil. Water has a density of 1 kg per litre. (All approximate.)
So the answer is 6.785840132 Kg/s and 8.482300165 L/s?
 
Yes.
But I would round these numbers to something sensible, like 2 sf. depending on the question's request. Since all the measurements are given to only 2 sf, you can hardly get a more accurate answer. If the question specifies that they are accurate to more figures, like RD = 0.8000 and pipe is 30.00mm and flow is 12.00 m/s even though these extra figures are not shown, then a more accurate answer would be appropriate.
 
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