Saved Bookmarks
| 1. |
A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m3 in 12 min. If the tank is 40 m above the ground, and the efficiency of the pump is 40%, how much electric power is consumed by the pump ? |
|
Answer» nfo : A pump on the ground floor of a BUILDING can pump up WATER to fill a tank of volume 30 m³ in 12 min. If the tank is 40 m above the ground, and the efficiency of the pump is 40%. To find : how MUCH electric POWER is consumed by the pump ? solution : mass of water pumped up to fill the tank , m = volume × density of water = 30 m³ × 1000 kg/m³ = 30,000 kg height of the tank from the ground, h = 40 m so potential energy of water, U = mgh = 30,000 kg × 10 m/s² × 40 m = 12 × 10⁶ J power required to pump up water = (Energy/time) = 12 × 10⁶/12 × 60 W = (1/60) × 10⁶ W but efficiency of motor is 40 % so, electric power consumed by motor = Power required to pump up water × 100/40= (1/60) × 10⁶ × 100/40 W = 41.67 kW Therefore electric power consumed by the pump is 41.67 kW |
|