Question of units in an equation:

Originally posted by AThousandYoung
A = 4GM/c^2R

G = 6.67428 x 10^-11 m^3/kg*s^2
M = 1.9891 ×10^30 kg
c = 299,792,458 m/s
R = 1.392×10^9/2 m = 6.96x10^8 m

4GM = 5.31032 x 10^20 m^3/s^2

c^2 = 8.9876 x 10^16 m^2/s^2

4GM/c^2 = 5.9085 x 10^3 m

4GM/c^2R = 8.489 x 10^-6 radians

I was careless with rounding; I rounded as I felt like it, not according to any kind of strict ...[text shortened]... significant digits. The small difference between your answer and mine should be insignificant.

A degree is pi/180 radians.
An arcminute is 1/60 degree.
An arcsecond is 1/60 of an arcminute.

According to wikipedia, this means that an arcsecond is 4.848 x10^-6 radians.

http://en.wikipedia.org/wiki/Minute_of_arc

Originally posted by AThousandYoung
A degree is pi/180 radians.
An arcminute is 1/60 degree.
An arcsecond is 1/60 of an arcminute.

According to wikipedia, this means that an arcsecond is 4.848 x10^-6 radians.

http://en.wikipedia.org/wiki/Minute_of_arc

Yep, you could also have just divided the 8.4E-6 by 1.75 and gotten the same thing. All interesting stuff, eh.

Originally posted by AThousandYoung
A = 4GM/c^2R

G = 6.67428 x 10^-11 m^3/kg*s^2
M = 1.9891 ×10^30 kg
c = 299,792,458 m/s
R = 1.392×10^9/2 m = 6.96x10^8 m

4GM = 5.31032 x 10^20 m^3/s^2

c^2 = 8.9876 x 10^16 m^2/s^2

4GM/c^2 = 5.9085 x 10^3 m

4GM/c^2R = 8.489 x 10^-6 radians

I was careless with rounding; I rounded as I felt like it, not according to any kind of strict ...[text shortened]... significant digits. The small difference between your answer and mine should be insignificant.

Thanks for verifying my calcs. I did it several times, the hardest part was getting 12 digits entered correctly in my 48, once I did that the same about three times I was satisfied I did it right...
I also generated my own constant, C^2, about 8.98 E16, so I wrote that down, it shows up so many times, now I don't have to do the math all over every time. That is in meters BTW.
I also worked up 4GR as a constant which doesn't change for the sun, comes in at about 5.3 E20. So the ones that just use 2GR, comes out to about 2.65 E20. Saves a lot of work don't you think?