A fun Celestial mechanics Question?

Question

OK you geniuses. Here is one in the field of celestial mechanics. Let's see who can figure out the correct answer to this one. (Totally hypothetical of course.) Good luck.

If the Earth was to suddenly double in size in both its diameter and it's density, which of the following things would occur as a result?

A) The speed of it's orbit around the Sun would slow down.
B) The speed of it's orbit around the Sun would increase.
C) The Earth's distant to the Sun would decrease due to gravity.
D) The Earth's distance to the sun would increase due to angular momentum.
E) The correct answer is actually A+C.
F) The correct answer is actually A+D.
G) The correct answer is actually B+C.
H) The correct answer is actually B+D.

(PS...Let's forget about the Moon for the sake of the question.)

*** Due to some Error with Yahoo, This same question got input twice. Feel free to answer the other one too. I will pick the same person for both if you are the first one to answer correctly. (Yes, I do know the answer to this myself.) ;-) ***

To Alexander. I hate when people come into a question just to tear it down. If you're so smart, then what is the correct answer? (I notice you didn't pick one.) Pay attention!! I SAID this was based on a totally hypothetical event. IF you could some how double the size and mass of Earth...ect. --- Next time, just don't answer a question you don't like. (Or one you find too hard to answer.)

Answer 1

D.

Answer 2

Well... Gosh - I'd say that since the sun is millions of times more massive than the Earth, it's speed and size of orbit about the sun wouldn't be affected... but, for the sake of arguement - I'd bet the Distance to the sun would decrease, as Earth's gravity well has expanded, and the speed of our orbit, likewise, would need to increase... So... G - B+C ???

Answer 3

All conservation laws are derived in assumption that mass doesn't change.

For example conservation of momentum is done like this:
F1 = -F2
m1a1 = -m2a2
m1 dv1/dt = -m2 dv/dt

BECAUSE MASS IS CONSTANT, mass can be placed inside differential:
d(m1v1)/dt = - d(m2v2)/dt
dp1/dt = dp2/dt
p1 + p2 = const

Whenever you say that mass magically changes, you have no right to apply any conservation law. Things like angular momenta become just useless products of something by something. Please, pass this to you teacher.