Question

A form of this quantity for a galaxy equals an observed form of this quantity over the sine of inclination. This quantity is measured via the tangent-point method at distances less than the galactocentric radius. Inferring this quantity from spectral line width enables estimation of a galaxy’s luminosity with the (*) Tully–Fisher (10[1])relation. (10[7])This quantity’s deviation from a Keplerian profile is evidence for dark matter, (10[1])as shown (10[1])on the vertical axis (10[1])of galaxy rotation curves. Hubble’s law equates a form of this quantity with Hubble’s constant times proper distance. Changes in frequency depend on relative values of this quantity in the Doppler effect. (10[1])For 10 points, name this quantity measured in kilometers per second. (10[3])■END■ (10[19])

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