Explain what is weight? How is it different from
mass?

The difference between mass and weight is that mass is the amount of matter in a material, while weight is a measure of how the force of gravity acts upon that mass. Mass is the measure of the amount of matter in a body. Mass is denoted using m or M.

Explanation:

this is poiselle's equation from fluid mechanic in physics. mech eng

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.