This activity assesses students’ ability to apply learning objective #2: Use Hub

This activity assesses students’ ability to apply learning objective #2: Use Hubble’s Law to intercompare distances to galaxies from redshift measurements.
Understanding Cosmological Redshift. Fill out the velocity column in the table above using RV calculator above or just your own calculator. In order to calculate v = zc in km/s, use the speed of light as 300,000 km/s.
Understanding the Hubble Law. For each galaxy’s velocity, fill out the two distance columns in the table using CT then CA.
Fill out the table and answer the questions below
Look at your calculated values for the velocity. What is wrong with them? What page(s) of the Content Slides explains how to fix the problem?
Was it easy for astronomers to find the value of the Hubble constant? Does everyone agree on it now? What page(s) of the Content Slides gives you this information?
Compare your distance values in the two columns. Are they the same or different? Do you know why?
Go back to CT and CA and enter 1 Mpc the distance in each. This gives d = v/H0 = 1 in Mpc units. What is the number for H0 for CT? For CA?
Using Dr. Weil’s Math shortcut. Looking at v = 30,000 km/s and v = 90,000 km/s? How many times bigger should the distance for 90,000 km/s be than the distance for 30,000 km/s? Is that true of the distances you found for CT and CA?
Using Dr. Weil’s Math shortcut. Looking at v = 30,000 km/s and v = 240,000 km/s? How many times bigger should the distance for 240,000 km/s be than the distance for 30,000 km/s? Is that true of the distances you found for CT and CA?
Do you need to know an exact value for the Hubble constant in order to use the math shortcut? Why or why not?