Each second, 1250 m3 of water passes over a waterfall 150 m high. three-fourths of the kinetic energy gained by the water in falling is transferred to electrical energy by a hydroelectric generator. at what rate does the generator produce electrical energy? (the mass of 1 m3 of water is 1000 kg.)

The generator produces electrical energy at a rate of 1378125000 J per second.

Explanation:

volume of water falling each second is 1250

height through which it falls, h is 150 m

mass of 1 of water is 1000 kg

⇒mass of 1250 of water, m = 1250×1000 = 1250000 kg

acceleration due to gravity, g = 9.8

in falling through 150 m in each second, by Work-Energy Theorem:

Kinetic Energy(KE) gained by it = Potential Energy(PE) lost by it

⇒KE = mgh

        = 1250000×9.8×150 J

        = 1837500000 J

Electrical Energy = (KE)

                            = ×1837500000

                            = 1378125000 J per second

the device is called “ rocket engine”

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.