Normal force for the rock because that makes an object stable at its position.
static friction because micro-welts hold its particle on its position so it doesn't change in position by a potential energy. Gravity makes it stay on the ground because its force attraction between an object and the earth.
Hope this helps <span />
Answer:
Q = 913.9 gpm
Explanation:
The Hazen Williams equation can be written as follows:

where,
P = Friction Loss per foot of pipe =
= 4 x 10⁻⁴
Q = Flow Rate in gallon/min (gpm) = ?
d = pipe diameter in inches = (400 mm)(0.0393701 in/1 mm) = 15.75 in
C = roughness coefficient = 100
Therefore,

<u>Q = 913.9 gpm</u>