Ans: Help With Astrophysics: Calculate 1600 Light Years Distance & Luminosity

[faisal]

Show that 1600 light years is equal to a distance of 1.5x10exp19 ?
my answer
1600x365x24x60x60=wrong answer
The black Hole was detected because of its effects on its neighbouring star. why do astromers have to rely on indirect evidence for looking at stars?
A star has a a radius of 9x10exp7 calculate its lumanosity
my answer
4X3.14X2.025EXP15=2.54X10EXP16
Help would be very welcomed.
thank you

 

[Doc Al]

Show that 1600 light years is equal to a distance of 1.5x10exp19 ?
my answer
1600x365x24x60x60=wrong answer

A "light year" is a measure of distance, not time. You calculated the number of seconds in 1600 years, which is not the question. How far does light travel in one year? What's the speed of light?

 

[faisal]

How far is a light year? 10 trillion kilometers -its a guess-

 

[Doc Al]

How far is a light year? 10 trillion kilometers -its a guess-

Why guess? Either look it up or look up the speed of light and calculate how far it travels in a year. Distance = speed X time.

 

[faisal]

1600x9.5exp12=1.52exp16

 

[faisal]

it was not a guess my friend here's the link
http://www.hartrao.ac.za/other/howfar/howfar.html

 

[Doc Al]

it was not a guess my friend ...

You were the one who said "it's a guess".

 

[faisal]

the speed of light = 299 792 458 m / s

 

[Curious3141]

No of meters light travels in a second = 299,792,458 (approximately)
No of seconds in a year = ? (work it out)
Hence no of meters light travels in a year = ? (this is one light year, measured in meters)

Hence 1600 light years = ? meters

 

[kathykoo9]

if your entire mass were to be converted to pure energy, how long could you proviede a MegaW (10^6 W) of energy to help in solving our energy crisises?

 

[kathykoo9]

help!

how much more or less would you weigh (same as force) at the surface of the sun than on earth?