# Thread: Application to Physics and Engineering Example (not asking to solve, just explain!)

1. ## Application to Physics and Engineering Example (not asking to solve, just explain!)

Hey! This is my first time using these forums so I appologize if I'm not following the proper protocol. I'll delete the thread once I get an explanation for my question. I'm just confused about a step in an example in the book. The question with pictures can be found on this PDF on page 8 with their solution: http://cims.nyu.edu/~kiryl/teaching/...ngineering.pdf
If you don't trust links the question is: EXAMPLE: Find the hydrostatic force on one end of a cylindrical drum with radius 3 ft if the drum is
submerged in water 10 ft deep. At one point in their explanation they state that the pressure on the strip is approximately 62.5(7 - yi*). I have no idea where this 62.5 value came from. Could you guys explain? Thanks in advance!

2. ## Re: Application to Physics and Engineering Example (not asking to solve, just explain

62.427 is the density of water in pounds per cubic foot.

Though I will admit that I'm not sure why it's taking only the density and the depth while the pressure formula is given by $\displaystyle P=h\rho g$

h = height or depth
rho is the density of the liquid
g is the acceleration due to gravity (which has been omitted in the pdf.)

EDIT: Okay, the conversion I used included gravity in the calculations

3. ## Re: Application to Physics and Engineering Example (not asking to solve, just explain

Originally Posted by Unknown008
62.427 is the density of water in pounds per cubic foot.

Though I will admit that I'm not sure why it's taking only the density and the depth while the pressure formula is given by $\displaystyle P=h\rho g$

h = height or depth
rho is the density of the liquid
g is the acceleration due to gravity (which has been omitted in the pdf.)
lbs/ft^3 is weight density = (mass density)g ... "g" is already figured in