Impedance is measurable by controlling either force or velocity

Evidence

To measure impedance, we can control the force and then measure the resulting speed—that is, control the numerator and measure the denominator in expression 1.7. Or we can control the speed of the point of application, and then measure the force that is needed to maintain that speed—that is, we can control the denominator and measure the numerator in equation 1.7. If the force or the velocity is controlled at the same spot on the object, the same value for the impedance is obtained either way. Extended objects will have different impedances depending on where the force is applied. — Eric J. Heller, Why You Hear What You Hear- An…, 90

Categorization

• DEFINE: Defines the operational measurement of impedance, showing the two complementary experimental setups produce the same value.