A laboratory report states: "The diameter of a ball bearing was measured times with a…

PHYSICS · Multi-part · Fermi University Physics · Scientific Practice & Experimental Methods · Uncertainty in measurement · Uncertainty in measurement

Measurement and Method, Ch Repeated readings: scatter, the mean and the standard error

Problem

A laboratory report states: "The diameter of a ball bearing was measured

25

times with a micrometer screw gauge. The readings gave a mean of

6.020\,\mathrm{mm}

and a sample standard deviation of

s=0.050\,\mathrm{mm}

. We report: diameter

= (6.020 \pm 0.050)\,\mathrm{mm}

N=25

." ((a)) Find the error in this report. ((b)) Write the diameter in house form

\bar x \pm u(x)

, stating what the

\pm

means and naming one effect (for example, the micrometer's zero error) that this figure does not include.

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