{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

problem_3 - ASTRONOMY 294Z The History of the Universe...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
ASTRONOMY 294Z The History of the Universe Professor Barbara Ryden Problem Set # 3 Due Tuesday, January 29 at class time NAME (please print clearly): SCORE (instructor use only):
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
1) [20 points] You are given a ticket for running a red traffic light. For an observer halted at the red light, the light emits a wavelength λ 0 = 700 nm. You tell the traffic cop that because you were approaching the light, the Doppler shift made it appear green ( λ = 500 nm). How fast would you have been going if this were true? If the speed limit is 35 miles per hour, and the speeding fine is $1 for every mile per hour over the limit, how large a fine would you have to pay? [Hint: 1 kilometer = 0.621 miles, 1 hour = 3600 seconds.]
Image of page 2
2) [20 points] Assume that a typical galaxy contains 100 billion stars, and that there is one galaxy per cubic megaparsec, on average. How many galaxies are within a Hubble distance, c/H 0 = 4300 megaparsecs, of us? How many stars are within a Hubble distance of us?
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
3) [20 points] The Sahara has an area of A = 9 , 000 , 000 square kilometers.
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}