Guest Aries0186 Posted April 6, 2004 Share Posted April 6, 2004 Spring break has ended and now I'm back in school and also new to the forums. This question I have is a review from Physics 20 and I have forgotten how to do it.... Question: The nearest star, Alpha Centauri A, is 4.07 x 10^16 m from Earth. a. How many light years is it away from Earth? b. What is the advantage of stating stellar distance in light years rather than meters? Part A, I got stuck because I don't know wheither to use the distance from the star to Earth, or the 9.46 x 10^15 m which is the distance light can travel in 1 year. If anyone can explain or help me, it would be much appreciated. Thanks. Link to comment Share on other sites More sharing options...
fafalone Posted April 6, 2004 Share Posted April 6, 2004 You need to convert meters to light years, so divide the distance by the distance light travels in a year, and you have light years it takes for light to get there. For part b, the answer they're looking for is that using light years requires the use of smaller exponents, so is supposedly more easy to grasp. The light year really isn't used for distances beyond our own small corner of the galaxy... for things on the other side of the galaxy, and anything that's not in our own galaxy, the most common unit of measurement is the parsec (intergalactic distances are typically given in Mpc, megaparsecs). Link to comment Share on other sites More sharing options...
Guest Aries0186 Posted April 6, 2004 Share Posted April 6, 2004 So the answer is....4.30 light-years (to 3 sig digs)? Link to comment Share on other sites More sharing options...
wolfson Posted April 6, 2004 Share Posted April 6, 2004 Light year is distance light travels in a year: Light travels at approx 3.0e8 m per second So in a year: Light travels = 3.0e8 * 60 *60 * 24 * 365 = 9.4608e15 Light year(s) from earth = 4.07e16 / 9.4608e15 = 4.30(1961779). Yes that correct Link to comment Share on other sites More sharing options...
YT2095 Posted April 6, 2004 Share Posted April 6, 2004 a) 4.30 is good b) because giving the distance in meters is far too cumbersome, light years are used as way of putting not to fine but still accurate perspective on the distances involved [edit] imagine expressing the distance from one English town to another town in the USA using Milimeters? it`s the same kind of thing with light years 2 Link to comment Share on other sites More sharing options...
aommaster Posted April 6, 2004 Share Posted April 6, 2004 good example YT. I remember those days where we thought light years was a measurement of time! The name is misleading though! Link to comment Share on other sites More sharing options...
Guest Aries0186 Posted April 19, 2004 Share Posted April 19, 2004 Okay....it's been a long time since I posted. I just have 1 question this time. The question is: What is the environmental significance of the amount of fossil fuel use? Link to comment Share on other sites More sharing options...
aommaster Posted April 20, 2004 Share Posted April 20, 2004 Well, the more fossil fuels you burn (in quantity) the more carbon dioxide is released from them. This causes global warming. It would melt the ice caps, and cause the sea level to rise, a maximum of 78 metres? is that enough info? I'm sort of a person that loves to protect the enivronment. So, I know quite a lot about it! Link to comment Share on other sites More sharing options...
YT2095 Posted April 20, 2004 Share Posted April 20, 2004 you could also include NOx and SO radicals that can reform into acid rain. Link to comment Share on other sites More sharing options...
aommaster Posted April 20, 2004 Share Posted April 20, 2004 yeah? I didn't know that! Link to comment Share on other sites More sharing options...
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