User talk:Duckster214

What do you mean by .005 & .005% don't mean the same thing? (In regard to hyper velocity stars? Thanks!

Hello- I guess that question was directed to me, so here's the answer. It just comes down to an understanding of what the percent sign means- this is not just related to the article in question, but it's what "percent" means in general (it's the same for interest rates or any other situation where you're using percentages). Essentially, the way to think about it is that the % sign means "divided by 100" (i.e. "per cent"). For example, 1% of $1 means 1/100 * $1, or 0.01 * $1, which is equal to 1 cent. But, 0.01% of $1 is equal to 0.01 * 0.01 * $1 which is equal to 1/100th of 1 cent.

Or, for another example: 25% of the speed of light doesn't mean 25*c, it means (25/100)*c = 0.25c.

For the star in question in the article you were looking at, if the star's measured speed is v = 1500 km/s, and c=300,000 km/s, then v/c = 0.005. Or you could write v = 0.005c. This is the same as writing that v = 0.5% of the speed of light, since v = 0.5 * 0.01 * c. In the same way that 25% of c means 0.25c, it's also the case that 0.5% of c means 0.005c. So, the correct statement is either that the star's speed is 0.5% of the speed of light, or that the star's speed is 0.005*c.

If you write "0.005% the speed of light", that means 0.005 * 0.01 * c, which is 0.00005c, which is equal to 15 km/s.

I hope that helps. See the article on percentage for more information, especially the paragraph that begins with "It is not correct to divide by 100...". That paragraph basically explains the same thing that I've explained above. Aldebarium (talk) 00:32, 22 December 2017 (UTC)[reply]