Hubble's law: Redshift measurements on a galaxy show that it is receding from us with a velocity of 7240 km/s. Estimate how far away the galaxy is if the Hubble constant is 22 km/s per million light-years. (c = 3.00 × 10⁸ m/s, 1 ly = 9.461 × 10¹⁵ m, 1 y = 3.156 × 10⁷ s) A) 3.1 × 10²⁴ m B) 1.2 × 10²⁶ m C) 1.2 × 10²⁴ m D) 4.1 × 10²³ m E) 2.0 × 10²² m

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Quizplus · Accepted Answer

Hubble's law states that the velocity of recession of a galaxy is proportional to its distance from us. The Hubble constant is the proportionality constant. In this problem, we are given the velocity of recession of a galaxy and the Hubble constant. We can use these values to calculate the distance to the galaxy.v = H0 * d7240 km/s = 22 km/s per million light-years * dd = 7240 km/s / (22 km/s per million light-years)d = 3.3 × 10^8 light-yearsd = 3.3 × 10^8 light-years * (9.461 × 10^15 m/light-year)d = 3.1 × 10^24 mTherefore, the distance to the galaxy is 3.1 × 10^24 m.

Hubble's Law: Redshift Measurements on a Galaxy Show That It