(a) A person's blood pressure is measured to be 120 ±2 mm Hg . What is its percent uncertainty?

step 1 So for Part A here, we're looking for the percent uncertainty. And so we're going to use the equ

(a) A person's blood pressure is measured to be 120 ±2 mm Hg...

(a) A person's blood pressure is measured to be $120 \pm 2 \mathrm{mm} \mathrm{Hg} .$ What is its percent uncertainty? Assuming the same percent uncertainty, what is the uncertainty in a blood pressure measurement of $80 \mathrm{mm}$ $\mathrm{Hg} ?$

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Key Concepts

Absolute Uncertainty

Absolute uncertainty is the margin of error attached to a physical measurement. It quantifies the amount by which the measured value can vary and is expressed in the same units as the measurement itself. This concept is essential for understanding the precision of an instrument and for reporting any measured quantity with an associated error range.

Relative (Percent) Uncertainty

Relative uncertainty refers to the ratio of the absolute uncertainty to the measured value, often expressed as a percentage. This measure provides insight into the significance of the uncertainty in relation to the size of the measurement. Percent uncertainty is useful for comparing the precision of measurements regardless of their units or scale.

Scaling of Uncertainty

Scaling of uncertainty involves applying the same relative error to different measured values. When the percent uncertainty remains constant, the absolute uncertainty for any new measurement can be determined by multiplying the new measurement by the given relative error. This concept is key when extrapolating or comparing measurements taken under similar conditions.

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