Answer:
A. The upward pressure gradient force is balanced by gravity.
Explanation:
A. is correct because the pressure difference is actually generated by gravity. As in the following formula for the pressure at different points:

where
are the pressure at 2 points, ρ is the density of the fluid, g is the gravitational constant, and h is the height difference.
B is incorrect because friction in air is too small to make an effect.
C is incorrect because the Coriolis force is horizontal, not vertical.
D is incorrect because a difference of 500 hPa = 50000 Pa, this is half of the atmospheric pressure.
E is incorrect because temperature cannot generate force.
Okay, first off, the formula for Kinetic Energy is:
<em>KE = 1/2(m)(v)^2</em>
<em>m = mass</em>
<em>v = velcoity (m/s)</em>
Using this formula, we can then calculate the kinetic energy in each scenario:
1) KE = 1/2(100)(5)^2 = 1,250 J
2) KE = 1/2(1000)(5)^2 = 12,500 J
3) KE = 1/2(10)(5)^2 = 125 J
4) KE = 1/2(100)(5)^2 = 1,250 J