Use the speed of light n a vacuum (299,792,458 m/s) 2 determine how many km a laser beam pulse travels in 1 hr

Question

If anyone can help me out, it'd be REALLY helpful!

thanks!

Answer 1

The speed of light in a vacuum is 299,792, 458 meters per second. Therefore, if it travels for 1 hour (60 minutes of 60 seconds each or 3600 seconds) it will travel for ? Do the multiplication.

Answer 2

This is called a light-hour and like a light-year, it sounds like a measure of time, but it is actually a measurement of distance. It is the distance that light, or any electromagnetic wave, travels in that number of absolute earth seconds. The laser beam pulse is not important. A photon from a light bulb will do exactly the same thing.
To find your answer simply multiply the speed of light (in m/s) by the number of seconds in 1 hour.

3.000 X 10^8 m/s X 60 min/hr X 60 sec/hr = (3 X 6 X 6) X (10^8 x 10 X 10) X (m/s) X (min/hr) X (s/min) = (36X3) X 10^10 x(m/hr) = (90 + 36) x 10^10 (m/hr)= 126 x 10^10 m/hr = 1.260 x 10^12 m/hr = 1 light hr.
Notice that even though you have a value for c that is 9 digits long and you can get one which is even more precise, that you did not give an error for that number the +/- that comes after it and civil engineers which deal with real world problems say that it is useless to use more the 3 significant digits in any work involving any humanly made measurement (except values like seconds and minutes that are 60 by definition and you can put as many zeros after them as you like, but they are exactly 60) unless the first number is 1. The other rules about significant digits still apply.
Lots of people get the idea of a light year wrong, even the guy who wrote my college engineering physics book. In an example he had a person travelling slower than the speed of light going 4 light years in 4 years (and you have to have that PhD to teach college. Wow -- go figure!)

Answer 3

very easy, two unit conversions.
speed of light (m/s) * (3600s / hr) * (1km / 1000m) = answer