Ming measures a recession velocity of 2000 km/sec for a galaxy. About how far away is that galaxy if the Hubble constant is 20 km/sec/million light years? (Hint: be sure to check the units in your calculation.)

Question

Quizplus · Accepted Answer

We can use the formula v = H0*d where v is the recession velocity, H0 is the Hubble constant, and d is the distance to the galaxy. Rearranging this equation gives d = v/H0. Substituting the given values, we get d = 2000 km/sec / (20 km/sec/million light years) = 100 million light years. Therefore, the best choice is C.

Ming Measures a Recession Velocity of 2000 Km/sec for a Galaxy