I get this.
The problem consists of sum of two pressures which the pump must create
- Pressure due to height of
#40 m#of water column
- Pressure due to jet of water at a rate of
For 1. Assuming unit area, Force
#40m#water column #P_1=mg=rhoxx"volume"xxg#
For 2. Assumed area of the jet be unit area.
Speed of water outlet from jet
Total mass of water thrown out per sec
Pump must exert pressure to support weight of this additional column of water of unit area
For unit area of jet pressure
Total pressure of the pump