A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, the power consumed now will be _____________ hp?

Question

Accepted Answer

0.5. Power in a centrifugal pump is proportional to the square of the speed (P ∝ N²). Halving the speed reduces power by a factor of four (1/2)² = 1/4. Thus, the new power is 4 HP * (1/4) = 1 HP. Wait, the options suggest 0.5 HP. If Power is proportional to Speed^3 for constant head and flow, then P_new / P_old = (N_new / N_old)^3 = (1/2)^3 = 1/8. New power = 4 HP * (1/8) = 0.5 HP.