You may find it helpful to review Chapter $7,$ Section $7\mathrm{.}1$ "Pressure in fluids" and Study session $11\mathrm{.}1$ "Fluid properties and hydrostatics" before attempting this question.

A hydraulic accumulator tower contains a vertical cylinder within which is a freely$-$moving piston lifting a ballast weight. If the cylinder is $85cm$ in diameter and the combined mass of the piston and ballast weight is $40$ tonnes, what is the pressure at the bottom of the water column when the piston has been lifted by $23m?$

The density of water is $1000kg{m}^{-3}$ and you should use $g=9\mathrm{.}81m{s}^{-2}.$

Give your answer in kPa to $2$ s$.$f$.$

Suggested approach: Pressure is required both to support the water column and to support the piston.

Pressure: kPa