a fountain sends a stream of water 19.8 m up into theair. The acceleration of gravity is 9.8m/s2. If thebase of the stream is 13.1 cm in diameter, what power is requiredto send the water to this height? Answer in W. 1) 29847.1 2) 36827.3 3) 13735.7 4) 8144.79 5) 31796.7 6) 2417.15 7) 42387.8 8) 11372.3 9) 51521.0 10) 47219.8 a fountain sends a stream of water 19.8 m up into theair. The acceleration of gravity is 9.8m/s2. If thebase of the stream is 13.1 cm in diameter, what power is requiredto send the water to this height? Answer in W. 1) 29847.1 2) 36827.3 3) 13735.7 4) 8144.79 5) 31796.7 6) 2417.15 7) 42387.8 8) 11372.3 9) 51521.0 10) 47219.8
Explanation / Answer
For the water molecules to go to the specified heighth, use mv2/2 - mu2/2 = -mgh byconservation of energy => 0 - mu2/2 = mgh => u =(2gh) => Initial kinetic energy = mu2/2 = mghfor each particle. Thus, the amount of power = Kinetic energytransferred/unit time = Total mass * g * h / 1 W = Area * speed*density*9.8*19.8 =*(0.131/2)2*(2*9.8*19.8)*1000*9.8*19.8W = 51521.0 W