The masses of the object and the planet it's on, and the distance between their centers.
Answer:
$v_f = = 7.9 \times10^3 \text{ m/s }$
The answers to all three questions depend on WHICH branch
of Physics you're talking about . . . a piece of information you've
neglected to specify.
Answer:
1) the strong nuclear force, 2) the electromagnetic force, 3) the weak nuclear force, and 4) gravity.
Explanation: