Question

Suppose you are an engineer, and you are asked to measure the force on a supporting beam of a bridge. You measure it to be 50,067 lbs, but you know that your scale is only precise to ±400 lbs. How do you record this measurement in your final report to the client? (Keep in mind that you want to find the perfect way to express the number to give an idea of how precise it is.) Click the above link to submit a three sentence description, which includes: (5 pts) How you would record the measurement in the final report. (5 pts) Why you would record it that way.

Answer 1

Answer:

F = (500 ± 4) 10² lb

Explanation:

This is an exercise in the uncertainty or error of a measurement.

If a single measurement is made, the way to give the result is the measurement value plus the appreciation of the instrument that corresponds to the absolute error, in the form

           F = x ± Δx

           

For this, a suitable uniform is the use of scientific notation, where each magnitude is written with an integer and some decimals multiplied by an exponential.

           X = 50067 lb = 5.0067 10⁴ lb

the uncertainty is

           Δx = 400 lb = 4.00 10² lb

so the result for the report must be written

          F = (500 ± 4) 10² lb

where the significant figures are adjusted to the measurement error.

In the case of making a series of measurements, the value obtained is the average of the measurements and the error must be given by the standard deviation