Sig Figs query for a steady flow pipe

Click For Summary
SUMMARY

The discussion focuses on the correct application of significant figures (sig figs) in reporting experimental data related to the Reynolds number, specifically using the equation Δp=(ρwater-ρatm)gΔ(Zw). The user is advised to round the final results to two significant figures, aligning with the lowest significant figure of the measurements used in calculations. It is emphasized that while reported values should be rounded, calculations should utilize full precision or include guard digits to maintain accuracy.

PREREQUISITES
  • Understanding of significant figures in scientific measurements
  • Familiarity with the Reynolds number and its significance in fluid dynamics
  • Basic knowledge of pressure calculations using manometers
  • Proficiency in using equations involving density and gravitational force
NEXT STEPS
  • Study the concept of guard digits in numerical calculations
  • Learn about the implications of significant figures in experimental physics
  • Explore the relationship between pressure and fluid dynamics in greater detail
  • Review best practices for reporting experimental data in lab reports
USEFUL FOR

Students in physics or engineering disciplines, laboratory technicians, and anyone involved in conducting and reporting experimental research related to fluid dynamics.

shortbread
Messages
1
Reaction score
0

Homework Statement



First let me say I'm new to lab reports at Uni, and I'm dreadful at them...

I'm having issues with how many sig figs to correctly display on a data table for an experiment I've done to investigate the Reynolds number. One particular step is to find Δp at different stages on a manometer using the equation Δp=(ρwater-ρatm)gΔ(Zw) with Zw being the difference between the left and right hand side of the manometer. all my Zw values are in mm; for example one of them is 33mm, using the equation for that particular value I get 323 Pa, I've looked around and it seems that the value I should display on the table is 320 Pa as the value I obtained should have the same SF as the lowest SF of the value used to calculate it. This seems ok for lower values but looks wrong at higher values because it feels like I'm rounding up and down a lot of the value. I would be thankful if someone could tell me if I'm going wrong and the correct procedure when dealing with SFs from measurements taken in experiments.

Homework Equations



-

The Attempt at a Solution



-
 
Physics news on Phys.org
What do you mean with higher values?
Rounding to two significant figures is fine for a final result. It is not a proper treatment of uncertainties anyway...
 
Don't mistake reported values for those used in calculations. Your report should contain rounded numbers, but you should never used these rounded values in your calculations. Use either full precision as spit out by your calculator, or at least use so called guard digits - that is, use several digits more than you are reporting.
 

Similar threads

How Do Viscous Interactions Differ in Vertical and Horizontal Geometries?
  • · Replies 31 ·
2
Replies
31
Views
4K
Effect of distance on jet force
  • · Replies 3 ·
Replies
3
Views
2K
Crude Oil Flow Rate Calculation: Viscosity & Reynolds Eq.
  • · Replies 5 ·
Replies
5
Views
4K
Fluid Dynamics Question - Pressure Difference in Horizontal Pipe
  • · Replies 1 ·
Replies
1
Views
4K
Thermodynamics: Vertical pipe flow of geothermal water
  • · Replies 1 ·
Replies
1
Views
2K
Fluid Dynamics in Pipe Lines Problem
  • · Replies 1 ·
Replies
1
Views
1K
Need help working out flow rate of gas from a compressor down a pipe please.
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad Fluid mechanics of water in a pipe
  • · Replies 6 ·
Replies
6
Views
5K