The water pump delivers 300 liters of water per minute to a height of 20 meters.

The water pump delivers 300 liters of water per minute to a height of 20 meters. Determine the power of the pump motor if its efficiency is 80%.

Data: V (water volume) = 300 l (300 dm3; 0.3 m3); t (duration of the water pump) = 1 min (60 s); h (lifting height) = 20 m; η (efficiency of the water pump) = 80% (0.8).

Constants: g (acceleration due to gravity) ≈ 10 m / s2; ρ (water density) = 1000 kg / m3.

Let us express the power of the water pump motor from the formula: η = Nп / Nв.н .; Nв.н. = Np / η = Ap / (η * t) = ΔEp / (η * t) = m * g * h / (η * t) = ρ * V * g * h / (η * t).

Calculation: Nv.n. = 1000 * 0.3 * 10 * 20 / (0.8 * 60) = 1250 W (1.25 kW).