The concept required to solve this problem is hydrostatic pressure. From the theory and assuming that the density of water on that planet is equal to that of the earth
we can mathematically define the pressure as

Where,
= Density
h = Height
g = Gravitational acceleration
Rearranging the equation based on gravity

The mathematical problem gives us values such as:



Replacing we have,


Therefore the gravitational acceleration on the planet's surface is 
1. 25
2. 55-25 = 30
Hope this helps! :)
Yes it is possible. Momentum is calculated by the mass of the object times its velocity.
For example, say a bowling ball weighs 3.0kg and is travelling at a speed of 3.0m/s. Its momentum would be 3.0×3.0=9.0 kg·m/s.
Now say we have a baseball weighing 0.20kg and it is travelling at a speed of 47.0m/s. Its momentum would be 0.20×47.0=9.4 kg·m/s, which is more than that of the bowling ball.
Answer:
9.8 m / s^2
Explanation:
Assuming free fall====> there is no initial downward/upward velocity
Assuming metric units 78.4<u> m/s </u>
vf = a t
78.4 = a (8) shows a = 9.8 m/s^2
It has to be D because the arrow will drop as it moves, if it were a gun, you'd lead the target so fire below it, but due to it being an arrow, you aim high not low. Also, they didnt specify how fast anything is, so you'd probably miss if you actually did it.