Question

Work problem. Please check my work.

Answer 1

@ganeshie8 :)

Answer 2

Volume = length * width * h
V=12x(delta(x))
The mass = 1000 so we have 12,000x(delta(x))

Force = 12,000x(delta(x))(9.8)
F = 117,600x(delta(x))

Work: \[\int\limits_{0}^{4}117,600x(8-x)dx\]

Answer 3

Is that all correct? I seem to be deriving the wrong answer.

Answer 4

..or..we could do it another way :>

Answer 5

I don't know, I don't really understand what your final work equation really is so it's hard for me to see if you accounted for everything or not.

Answer 6

Basically though my way of thinking is a little bit of work is needed to take a little layer off the top the entire height and that height along with the volume of water you pump is dependent on the height of the water.

Answer 7

hmhm ok. So how do we set that up? :)
..is your answer coming out different to mine? (as in the picture)

Answer 8

\[p*g*1000*\int\limits_{0}^{4}(8y-y^2)dy\]this is another way we could set it up, it gets me the same answer though.

Answer 9

drawing it like this.

Answer 10

@rvc :)

Answer 11

@freckles

Answer 12

I found my mistake, it should be (7x-x^2)
so I think my answer is
4,076,800
is that correct?

Answer 13

or is it....4,547,200? (that's the answer a guy from my school says o.o) I think I have one try left so I don't want to put either in until someone here checks lol. HELP MEE. please D:

Answer 14

http://www.wolframalpha.com/input/?i=Integrate%5B%28c*b*h%2Fa*1000%29*9.8*%28d%2Ba-h%29%2C+%7Bh%2C0%2Ca%7D%5D

Answer 15

4,076,800 J

is correct

Answer 16

oh my gosh. Thank you so much:) I was so done with this problem =.=