Member of the Month

GayWolf420
June, 2025

Online

Welcome to the Newschoolers forums! You may read the forums as a guest, however you must be a registered member to post. Register to become a member today!

WIll paypal someone $2.00 if they can help me with math

profile picture
please
Posts: 96 - Karma: 600
i have spent hours on this problem and it is impossible, google hasn't helped

The ends of a water trough have the shape of the region bounded by the graphs of y = x^2 and y = 4 with x and y both measured in feet. To what depth must the trough be filled with water so that the force exerted by the water on either end of the trough is 779.423 lb? (Water has a density of 62.5 lb per cubic foot.)


answer choices are 2.452 feet, 2 feet, 3 feet, 2.351 feet, or 3.528 feet
11 years ago
34 2
profile picture
cheaaaaaa
Posts: 830 - Karma: 630
http://wolframalpha.com may be able to help, not sure tho
11 years ago
0 0
profile picture
Xanadoo
Posts: 729 - Karma: 1,237
two whole dollars?!?! wow! I could almost get a cup of coffee with that much money!
11 years ago
2 0
profile picture
op14
Posts: 1769 - Karma: 4,586
Don't plan on going to starbucks
11 years ago
11 0
profile picture
duuude.
Posts: 147 - Karma: 19
2.351 feet

11 years ago
0 0
profile picture
please
Posts: 96 - Karma: 600
do you have any work to be shown or any justification before i payal that shit to you
11 years ago
1 0
profile picture
Astomp
Posts: 10090 - Karma: 344
its actually 7. check one more time to make sure thats not a choice.
11 years ago
0 0
profile picture
ILLinoisance
Posts: 3527 - Karma: 5,398
3.528

Source: the bottom of this shitshow: http://openstudy.com/updates/4f5b9dd9e4b0602be437f13a
11 years ago
0 0
profile picture
Scaredwhiteboy
Posts: 1395 - Karma: -937
I'm 95% certain the answer is 3.528 ft.

The water pressure on the side of the trough is equal to the density of water multiplied by the depth at the point. So p = (d - y) * 62.5. To calculate the the force on the side of the trough, we need to multiply the pressure by the area. To do this we need an integral because the pressure on the side varies with depth. The area of a tiny of the side is 2 * sqrt(y) * dy. dy represents an infinitesimal vertical sliver of the trough, and 2 * sqrt(y) is the width of that sliver. To solve for the force we multiply the area by the force and take the integral from 0 to d (d is depth).

Your final equation should look like this: integral(62.5 * (d - y) * 2 * sqrt(y) * dy) from 0 to d. Setting this equal to 779.423 and solving for d, we get the depth to be 3.528 feet.
11 years ago
2 0
profile picture
notspoicey
Posts: 1167 - Karma: 1,708
Ummmmmmmmmmmmmm
11 years ago
0 2
profile picture
GayWolf420
Posts: 38263 - Karma: 131,720
X = 420
11 years ago
8 0
profile picture
BROLF
Posts: 1598 - Karma: 5,099
*3 hunna
11 years ago
5 0
profile picture
Loco-Deer-Slayer
Posts: 1401 - Karma: 701
You are pretty close and definitely approaching this the right way. This is obviously an integral problem but density multiplied by depth(area) does not equal pressure. You need to include the gravitational constant in there.

11 years ago
0 0
profile picture
Loco-Deer-Slayer
Posts: 1401 - Karma: 701
Fucked up my link…the one above is similar concept but different application. This is what you want:

11 years ago
0 0
profile picture
Loco-Deer-Slayer
Posts: 1401 - Karma: 701
Fucked up my link…the one above is similar concept but different application. This is what you want:

11 years ago
0 0
profile picture
Espen519
Posts: 552 - Karma: 969
I'm 12 and the answer is D:69
11 years ago
0 0
profile picture
Scaredwhiteboy
Posts: 1395 - Karma: -937
Don't listen to this idiot. He doesn't know what he's talking about. The given density is already in lbs so we don't need to do shit with gravity.
11 years ago
0 0
profile picture
yelsel
Posts: 12967 - Karma: 3,451
Wtf you seriously need to figure that out for a math class?! Fuck that
11 years ago
1 0
profile picture
SSteezle
Posts: 9458 - Karma: 2,342
x= 8008135 (.)(.)
11 years ago
0 0
profile picture
ricky2k15
Posts: 16 - Karma: 44
when in doubt choose C.
fuck it.
11 years ago
0 0
profile picture
Loco-Deer-Slayer
Posts: 1401 - Karma: 701
damn man so much butt hurt.

I was thinking lbs was newtons not just mass (SI unit habit). If you did what I said to do but with SI units we would get the same answer, but yes you are right.
11 years ago
0 0
profile picture
mski
Posts: 4791 - Karma: 3,802
I'm amazed you got some real answers

Thanks for getting me stoked that I never need to sit through another math class again. Hope that shit pans out for you tho!
11 years ago
1 0
profile picture
Byron_tha_gr8
Posts: 4573 - Karma: 14,304
what class is this so i can be sure to never take it?
11 years ago
0 0
profile picture
CaptainObvious.
Posts: 5713 - Karma: 20,652
OP I found your teacher and showed this thread.

ur fuqd
11 years ago
0 0
profile picture
trill
Posts: 297 - Karma: 1,670
14. the answer is always 14
11 years ago
0 0
All times are Eastern (-4); Currently it's 1:18AM