Re: ZetaTalk and Spaceguard UK (D4)

Bill Nelson has offered corrections (below) for some of the math used to place
Newton's Law    F=M*A
Inverse Square   F=M1*M2/r^2
on the same page with each other, using a REAL mass, the density of granite,
for the Earth and Moon.

Bill Nelson wrote:
> In sci.astro Nancy Lieder <zetatalk@zetatalk.com> wrote:
>> Conversely then, if the Moon has 1/4 the Earth's diameter, it's
>> volume would be 1/68th that of the Earth, correct?
>
> Close. It would be 1/64th the volume, in both cases. The volume of
> a sphere is directly proportional to the cube of the radius.
>
>> My Britannica states that granite is 2.5-2.7 g/cm3
>> (cubic centimeter).  It also states that a metric ton is 1,000,000
>> grams.
>
> Wrong. A cubic km contains (10^5)(10^5)(10^5) or 10^15 cm3.
> That cubic km of granite will thus weigh 2.5*10^15 grams - or
> 2.5*10^9 metric tons.

How does that change, if at all, the base figures, below?

Earth diameter of 12756.27 km.
Moon diameter of  3444.193 km.
using volume of sphere as 4/3*Pi*R^3
volume of Moon is 0.019683 of Earth
Earth is 1,083,157,900,000 km^3 in volume
Moon is 21,998,936,949 km^3 in volume

a metric ton is 1,000,000 grams
granite density as 2.64-2.76 g/cm^3
Earth: 2,707,894,750,000,000,000,000 Metric Tons
Moon: 54,997,342,400,000,000,000 Metric Tons

Eric's reference Earth density: 5.5170 g/cm^3
Eric's reference Moon density: 3.3411 g/cm^3
Earth: 5.9763e+24 kg ( 5.9763e+21 Metric Tons)
or  2.70789475e+21 Metric Tons
Moon: 7.3508e+22 kg ( 7.3508e+19 Metric Tons)
or  5.49973424e+19 Metric Tons
or 73,696,438,000,000,000,000 Metric Tons

gravitational equation F = G*m1*m2/r^2
acceleration of the moon due to gravity toward the Earth
F = 2.20228796E+16 metric ton force
or =  20,228,796,000,000,000 metric tons-force

C  = Pi*2*R = Pi*D
C =  2415768.45 km
gives a circular orbital speed of: 1023.183 m/s