# word problem question

• Mar 15th 2009, 02:16 PM
math1645
word problem question
the speed of light is 1.863 x 10^5 miles per second.

assume 1 year is 365 days. write an expression to convert speed of light from miles per second to miles per year

make a table that shows the distance light travels in 1, 10, 100, 1000, 10000, 100000 years. our galazy has a diameter of about 5.875 x 10^17 miles. based on the tablem about how long would it take for light to travel across our galaxy.

i have no idea what to do. help
• Mar 15th 2009, 03:24 PM
HallsofIvy
Quote:

Originally Posted by math1645
the speed of light is 1.863 x 10^5 miles per second.

assume 1 year is 365 days. write an expression to convert speed of light from miles per second to miles per year

make a table that shows the distance light travels in 1, 10, 100, 1000, 10000, 100000 years. our galazy has a diameter of about 5.875 x 10^17 miles. based on the tablem about how long would it take for light to travel across our galaxy.

i have no idea what to do. help

You are given the speed of light as $1.863 x 10^5$ mi/s. There are 60 s/min, 60 min/hr, 24 hr/day, and 365.25 day/yr. Notice how if you multiply those "fractions" together everything cancels except mi/yr?