v = SQrt(G*Mbh)/R where G is the gravitational constant of 6.673*10^-11NM^2/kg^2, v is 1.3*10^7KMh, and R = 9.61*10^5 KM

To solve for Mbh, we will rewrite the equation as this:

(Rv^2)/G = Mbh

Then plug in the numbers:

(9.61*10^5 * (1.3*10^7)^2) / 6.673*10^-11 = Mbh

(9.61*10^5 * 1.69*10^14) / 6.673*10^-11 = Mbh

2.43*10^30kg

By comparison, the mass of our sun is 1.99*10^30, so the BH is only slightly more massive than our own Sun.

Some of you may be thinking that this mass may be too low for a stellar mass BH, seeing that it just barely below the Chandrasekhar limit (1.4MSol or 2.765*10^30) – but remember that we were given approximations of the distance the WD is orbiting as 2.5LD, and the time to orbit being exactly 28 minutes. These approximations will invariably contaminate the mass calculations.

]]>distance given is 2.5 times distance Earth-Moon or

which gives a radius of 384,400 km × 2.5 = 961,000

orbit length equals circumference of circle or 2×pi×r

total length equals: 2 × pi× 961.000 km = 6 mega km

time to complete orbit is 28 minutes

speed is 60 minutes / 28 minutes × 6 Mkm = 13 Mega km/h

conversion to miles:

easy conversion value: 3/5 × 13 Mega km/h = 8 Mega mph

this is about 1.3% the speed of light.

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