Chegg Textbook Solutions for Pathways to Astronomy 3rd Edition:
Chapter 64  Chapter: Problem:  An interferometer measured the
change in radius of one Cepheid as about 10% during its 10-day
period. The star was measured to have an average radius of 40
million km. How fast was the surface of the star moving outward,
on average, if it took 5 days to expand by 10%?    • Step 1 of 1
(About 9.3 km/s). A 10 percent increase in a 40 million
kilometer radius is 4 million kilometers. So the surface of the
star moved outward 4 million km in 5 days. There are 432000
seconds in 5 days, so the speed was 4 × 106 km/432000s = 9.3
km/sec.  Select Your Problem  Get Study Help from Chegg