The appendices at the back of your textbook have a lot of useful information, including reviews of
simple problem solving. Read through them if you need to brush up on topics such as units or
scientific notation.

The following practice calculations should be completed before**Thursday May 10, 2018.**
Given below is the speed of light and three useful conversion factors, where
LY = light year and AU = astronomical unit. Aim for organization, accuracy, neatness, and clarity. Always
show your work (the various steps) for maximum credit.

2. How many years would an "astro car" moving at 60 miles/hour (100 km / hour) need to cover the above distance?

3. If a radar beam, moving at the speed of light, needs 12 seconds to go from the Earth to a comet and back, then how far away is the comet?

4. M33, alias the Triangulum Galaxy, is about 2,400,000 light years away. (a) How many AU away is M33? (b) How many miles away is M33?

5. Sirius, the brightest night-time star, is 8.58 light years from the Earth. (a) How many AU from the Earth is Sirius? (b) How many years would a beam of red laser light need to reach Sirius?

Answers are here!

The following practice calculations should be completed before

- Speed of light = 186,000 miles/ sec = 300,000 km / sec
- 1 LY = 63,240 AU

- 1 AU = 9.29 x 10
^{7}miles = 1.50 x 10^{8}km

- 1 LY = 5.88 x 10
^{12}miles = 9.46 x 10^{12}km

2. How many years would an "astro car" moving at 60 miles/hour (100 km / hour) need to cover the above distance?

3. If a radar beam, moving at the speed of light, needs 12 seconds to go from the Earth to a comet and back, then how far away is the comet?

4. M33, alias the Triangulum Galaxy, is about 2,400,000 light years away. (a) How many AU away is M33? (b) How many miles away is M33?

5. Sirius, the brightest night-time star, is 8.58 light years from the Earth. (a) How many AU from the Earth is Sirius? (b) How many years would a beam of red laser light need to reach Sirius?

Answers are here!

- Pages maintained by Dr. Reggie Hudson
- Last changed: December 8, 2015