If we allow for a simple runaway greenhouse effect, the inner ...

[gonzo233]

If we allow for a simple runaway greenhouse effect, the inner boundary of the Sun's habitable zone would be
 
  A) roughly halfway between the orbits of Venus and Mercury
  B) just outside the orbit of the planet Mercury
  C) roughly half way between the orbits of the Earth and Venus
  D) just inside the orbit of the Earth

Question 2

A mass which weighs 19.6 Newtons on Earth is 2.3 meters away from a 2.00 kg mass.
 
  (a) Determine their mutual gravitational attraction to each other.
  (b) How much work would have to be done to put a very large distance between the two masses?

[fur]

Answer to Question 1

C

Answer to Question 2

(a) 5.0  10-11 N
(b) 12.  10-11 Joules

[gonzo233]

Excellent

[amcvicar]

Great answer, keep it coming