This is simply referring to the fact that the gravitational pull of the earth is greater as you get closer to the surface of the earth, meaning that acceleration increases as well.
Explanation:
Let acceleration due to Gravity for a planet is given by:
Here,
Escape velocity is given by:
Here, 
and g_X = 2g
Therefore,
The asker of the second question needs a tutorial in radiometric dating. There is little likelihood that the daughter isotope has the same atomic weight as the parent isotope. To measure the mass isotopes doesn't tell us how many atoms of each exist. To get around that let's pretend — which will likely serve the purpose ineptly intended — that the values give an the particle ratio, 125:875.
<span>The original parent isotope count was 125 + 875 = 1000. The remaining parent isotope is 125/1000 or 1/8. 1/8 = (1/2)^h, where h is the number of half-lives. </span>
<span>h = log (1/8) ÷ log(1/2) = 3 </span>
<span>And 3 half-lives • 150,000 years/half-life = 450,000 years.</span>
The heat remains constant because there’s nothing to cool it down
