Answer
$980000 \ J$
Work Step by Step
The force of one layer is equal to:
$\ Force= \ Mass \times \ gravity = 9.8 \times (1000) \times 32 \Delta y \ N=313600 \Delta y \ N$
Therefore, the work done against can be computed as:
$ W=\int_{0}^{2.5} 313600 y \ dy \\=313600 [\dfrac{y^2}{2}]_{0}^{2.5} \\ =156800 [y^2]_{0}^{2.5} \\=156800 \times (2.5)^2$
By using a calculator, the required result is:
$W \approx 980000 \ J$
