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### Question about speed of light rounding

Posted: Sun Oct 15, 2017 5:16 pm
In problem 1.15 why did they round the speed of light (2.998 x 10^8) but in problem 1.17 they didn't (2.99792 x 10^8)?

### Re: Question about speed of light rounding

Posted: Sun Oct 15, 2017 5:18 pm
Our TA remarked about this in our discussion section to use the constants provided by Professor Lavelle on his website (subsequently the same for the test).

### Re: Question about speed of light rounding

Posted: Sun Oct 15, 2017 5:19 pm
I believe is that in problem 15, they had a number of 102.6, which has 4 significant figures so they round the speed of light to 4 sig figs. Meanwhile, in problem 17, they didn't specify a number so they used the actual number of the speed of light.

### Re: Question about speed of light rounding

Posted: Sun Oct 15, 2017 6:16 pm
Regarding the constant for the speed of light, should we always use 2.99792 x 10^8 or is it okay to round to 3.0 x 10^8? In the lectures 3.0x10^8 is used, but on the constants and equations sheet it says 2.99792 x 10^8

### Re: Question about speed of light rounding

Posted: Sun Oct 15, 2017 7:32 pm
I think using the value Dr. Lavelle provided on the constants and equations sheet will be the safest option then at the end round the result to the appropriate sig figs based on the problem.