astr100f2008hw1

# astr100f2008hw1 - ASTR 100 Homework 1 Solutions McGaugh...

This preview shows pages 1–2. Sign up to view the full content.

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ASTR 100: Homework 1 Solutions McGaugh, Fall 2008 1. Problem 1-15. “Our solar system is bigger than some galaxies.” This statement makes no sense. A galaxy is composed of hundreds of billions of stars, while our solar system is ‘just’ the stuff orbiting one star, our sun. Our solar system is a tiny part of the Milky Way Galaxy, being much smaller than it. 2. Problem 1-41. Distance by light: The problem asks you to compute the distance that light can travel in different intervals of time, measured in kilometers and miles. d = vt : distance = speed x time. In this case, the speed is the speed of light: v = c . According to Appendix A of the book, c = 3 × 10 5 km / s. The exact number is c = 299 , 792 km / s; it is OK to use either value. a) 1 light-second = (3 × 10 5 km / s)(1 s). The seconds cancel out (see Appendix C), so 1 light-second = 300,000 km. 1 km = 0.62 miles, so (300,000 km)(0.62 miles/km) = 186,000 miles. That’s a long way to go in one second! b) Similarly, 1 light-minute = (3 × 10 5 km / s)(1 minute). Be consistent in the use of units. 1 minute = 60 seconds, so 1 light-minute = (3 × 10 5 km / s)(60 s). Now the units again cancel nicely, and 1 light-minute = 1 . 8 × 10 7 km = 1 . 1 × 10 7 miles....
View Full Document

## This note was uploaded on 02/05/2009 for the course ASTR 100 taught by Professor Hayes-gehrke during the Fall '06 term at Maryland.

### Page1 / 2

astr100f2008hw1 - ASTR 100 Homework 1 Solutions McGaugh...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online