Uncertainty in Fluid Viscosity Measurement: Improving Result Presentation

In summary, a student conducted an experiment to determine the viscosity (ƞ) of water by measuring the flow rate (Q) through a horizontal pipe of length (l) and radius (r) under streamline conditions. The equation for flow rate is Q = (p/ƞ)πr^4/8l, where p is the pressure difference across the pipe. The student's result for ƞ was given as Q = (2.7 ± 0.2) × 10^-3 m^3/s, with estimated percentage uncertainties for Q, p, l, and r as 7%, 10%, 5%, and 3% respectively. However, the instructor deemed the result presentation unsatisfactory
  • #1
Diana Moceiparisi
1
1

Homework Statement


a) The equation governing the flow rate,
upload_2017-2-8_18-33-16.png
, of a fluid under streamline conditions through a horizontal pipe of length l and radius r is:

upload_2017-2-8_18-33-34.png


where p is the pressure difference across the pipe and ƞ is the viscosity of the fluid.

Thus, a student conducted an experiment in order to determine the value of ƞ of water and finally states his result as
upload_2017-2-8_18-33-54.png
and estimates the percentage uncertainties in his measurement of
upload_2017-2-8_18-34-13.png
, p, l, and r as
upload_2017-2-8_18-34-41.png
,
upload_2017-2-8_18-35-54.png
,
upload_2017-2-8_18-35-0.png
,and
upload_2017-2-8_18-35-29.png
respectively.

According to the instructor, although his arithmetic and the unit are correct, his statement is unsatisfactory. Thus, in order to improve the result presentation you are required to express his result with appropriate uncertainty.

Homework Equations

The Attempt at a Solution

 

Attachments

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  • #2
The "attempt at solution" image you uploaded appears only to say ##\frac{dv}{dt}##.
 
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1. What is uncertainty of measurements?

Uncertainty of measurements refers to the potential error or variability in a given measurement. It is a measure of how well the value of a quantity is known, and is often expressed as a range of values rather than a single, precise number.

2. Why is it important to consider uncertainty in measurements?

Uncertainty in measurements is important because it allows us to understand the limitations of our measurements and the potential for error. It also helps to ensure the accuracy and reliability of data, as well as the validity of conclusions drawn from that data.

3. How is uncertainty of measurements calculated?

The uncertainty of measurements is typically calculated using statistical methods, such as standard deviation or confidence intervals. It takes into account factors such as instrument error, human error, and natural variability in the measurement.

4. How does uncertainty of measurements affect scientific research?

Uncertainty of measurements can have a significant impact on the results and conclusions of scientific research. It is important for researchers to carefully consider and report the uncertainty associated with their measurements in order to accurately interpret their findings.

5. Can uncertainty of measurements be reduced?

While uncertainty of measurements cannot be completely eliminated, it can be reduced through careful experimental design, calibration of instruments, and minimizing sources of error. Repetition of measurements and using more precise instruments can also help to decrease uncertainty.

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