Question

Need help with rectangular tank work question

Answer 1

rectangular tank is 5 ft long 2 ft wide and 3 ft deep filled with a liquid with weight 100 lb per ft^3

Answer 2

How to find work?

Answer 3

let me provide a bit more info

Answer 4

how much work is used to pump 2/3rds of the water over the edge?

Answer 5

w= fxd = integral of :
1100(3-y)

Answer 6

because 5x2xdy = volume of a slice x 110lbs/ft^3 = 1100lbs Force

Answer 7

I do but it keeps telling me I am wrong
I dont know what Im missing

Answer 8

for the 2/3rds would it integral from 0 to 2 of 1100(3-y)?

Answer 9

Hmm it looks like you've written it's 110 lb/ft^3 and 100 lb/ft^3, maybe you mixed it up a little in your algebra?

Also, I believe your limits of integration are messed up. Let me think about it a second to make sure.

Answer 10

I think you should be using (y) instead of (3-y) in your integral from 0 to 2. The reasoning being that when you're trying to pump out the liquid at the beginning it will take almost no work since it's already at the top right? So it should start out as the distance being 0 and then work its way up to 2 feet.

When you calculate it as (y-3) from 0 to 2 you're saying the work at the beginning is moving it 3 feet and ends at moving it 1 foot. Also, you will get negative work done by the pump by doing it this way too, which I think is wrong in this context.

Answer 11

THANK YOU!

Answer 12

Thats it thank you so much!

Answer 13

Awesome! =)

Answer 14

So if you want to move all the water to a point 4 above that? Then replace y with (y+4) since that will be pushing the water an additional 4 always for each point. I believe that's what you're asking? I'm not entirely sure.