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Speed of Light

Posted: Tue Oct 10, 2017 12:52 am
Is it better to use c=3x10^8 or c=2.998x10^8 like it is stated in the textbook?

Re: Speed of Light  [ENDORSED]

Posted: Tue Oct 10, 2017 10:03 am
I haven't seen any specific guidelines but more significant figures will usually lead to the more accurate answer, so I wouldn't really recommend using 3.0 unless you're in a rush or something.

Re: Speed of Light

Posted: Wed Oct 11, 2017 2:39 pm
I think that it would be better to use 2.998x10^8 as the speed of light in order to get a more precise and accurate answer. However, using 3.00x10^8 won't dramatically affect your answer.

Re: Speed of Light

Posted: Wed Oct 11, 2017 3:20 pm
Typically, I use the more precise number because I try to limit the possible rounding errors that could affect my answer. I also try doing this by keeping the whole numbers in my calculator and try as little to possible to round until I get my final answer. However, as other people are saying, there is not much difference between 3.00x10^8 and 2.998x10^8, so there won't be a large effect on your answer.

Re: Speed of Light

Posted: Wed Oct 11, 2017 3:40 pm
Lavelle uses 3.00x10^8 when solving his problems, so I think it would be fine to use this one. Either will work though!

Re: Speed of Light

Posted: Wed Oct 11, 2017 3:58 pm
I prefer to use 2.998x10^8 because it gives a more accurate and precise answer. It's like when we calculated the moles in the previous chapter, we carried all the decimal points until the final answer then we rounded it. But if you feel more comfortable using 3.00x10^8 then it should be fine too. :)

Re: Speed of Light

Posted: Wed Oct 11, 2017 8:25 pm
My TA told us to use whatever number is given to us on the equation sheet on the front page of the test, just to be safe. But either way should work!

Re: Speed of Light

Posted: Thu Oct 12, 2017 1:13 am
If I need a precise answer, I use as many significant digits as I am given. However, if I am solving something for a ratio or something where rounding does not change the final outcome, I will use a more general number and save some time.

Re: Speed of Light

Posted: Thu Oct 12, 2017 1:50 am
I don't think that it really matters that much. Dr. Lavelle uses 3.00x10^8, so that should work. The 2.998x10^8 should be equally as good or better, since it is closer to the exact speed of light!