Math Help please. I need some equations

**Mike Hawk** · 02-19-2006, 04:57 PM

Heres a few math problems that i cant seem to find the equations for, if someone can help me out that would be great.

1. If 78 feet of water is present in a tank, what will the pressure be on the bottom of the tank?
a. 33.8 psi
b. 78 psi
c. 180 psi

2. Convert 30,000 gallons to cubic feet:

3. A trench that is 550 feet long, 3 feet wide and 10 feet deep will have how many cubic yards of soil removed?
a. 611
b. 1833
c. 5500

**INandOUTBurger** · 02-19-2006, 06:01 PM

Originally Posted by Mike Hawk

Heres a few math problems that i cant seem to find the equations for, if someone can help me out that would be great.

1. If 78 feet of water is present in a tank, what will the pressure be on the bottom of the tank?
a. 33.8 psi
b. 78 psi
c. 180 psi

.433 psi of "head" pressure per culumn foot

78' column height * .433 psi/foot = 33.774*

*note this calculation ignores the friction of the water against the pipe surface one would need to determine the type of pipe material and the diameter of the pipe and if need precision, the mineralization of the water before an exact calculation could be made

Originally Posted by Mike Hawk

2. Convert 30,000 gallons to cubic feet:

7.5 gallons per cubic foot = 30,000/7.5 = 4,000 cubic feet

Originally Posted by Mike Hawk

3. A trench that is 550 feet long, 3 feet wide and 10 feet deep will have how many cubic yards of soil removed?
a. 611
b. 1833
c. 5500

550' * 3' * 10' = 16,500' cubed 3' * 3' * 3' = 27' cubed or one cubic yard

16,500' cubed / 27' cubed = 611.1111111111r cubic yards*

*note this is the size of the area that the material was removed from one will need to test the soil type and moisture content and then consult their civil engineering text to determine how much said soil will fluff up when placed on the spoil pile

**the answers presented within are mearly for basic mathmatical practice and in no way should be used to determine the strenght of or types of materials used to construct and structure

failure to follow the above disclaimer could result in injury, structural failure or death

**ss~zoso~ss** · 02-19-2006, 06:44 PM

i like the little disclaimer

lol

good work

**Mr. CarelessAndImprudent** · 02-19-2006, 07:37 PM

Nice, what was that homework for

**ZAPFOOL!!** · 02-19-2006, 07:56 PM

someone has some engineering expericence and or knowledge

**oneBADDz** · 02-19-2006, 08:01 PM

Sweet, I am so glad to know I'm not the only nerd here. I was a math major in college. . .

**ZAPFOOL!!** · 02-19-2006, 08:02 PM

mechanical engineering degree here...

badass67 · 02-19-2006, 09:06 PM

I hope that Mikey takes note and doesn't just use the answers to pass a class

**SeVeReDiStOrTiOn** · 02-19-2006, 09:19 PM

Head hurts...must....lie down

Man I feel dumb...I tried figuring it out...then the front of my head started to hurt...fock that...where's my tv remote

**Mike Hawk** · 02-20-2006, 09:40 AM

cool, thanks burger, you da man

**predator** · 02-20-2006, 09:59 AM

DAMN IT!!!!... some one beat me too it... i was wanting to flex my BSME muscles... being they are the only ones i have...

-ME..... BSME

you know like bond.... james bond.... ouch flame on

BOOSTD · 02-20-2006, 06:50 PM

What class is this for? I have a more interesting addition to the third problem: Fill up the trench with water and let it leak out through a hole that is two feet in diameter. At the same time, a hose is draining water into the trench at 300 galons per min. Will the trench empty or will it overflow? If it will empty, how long will it take? Now THAT is a problem worth solving.

BOOSTD

**Mike Hawk** · 02-20-2006, 07:53 PM

its for a state license to become a water treatment operator, practice exam

**MyRed93z-28** · 02-24-2006, 06:22 PM

Originally Posted by BOOSTD

What class is this for? I have a more interesting addition to the third problem: Fill up the trench with water and let it leak out through a hole that is two feet in diameter. At the same time, a hose is draining water into the trench at 300 galons per min. Will the trench empty or will it overflow? If it will empty, how long will it take? Now THAT is a problem worth solving.

BOOSTD

I just did something similar to that in a lab in my thermo/heat power class except we didn't do it in a trench. The conservation of mass I think? I'm going for my Associates in MET right now. Taking 20 credit hours.....it sucks.