The sketch illustrates a common consumer product termed as Water Pik. This device uses a motor to drive a piston pump that produces a jet of water (diameter d = 3 mm, temperature T = 10 °C) with a speed of 25 m/s. Find out the minimum electric power in watts which is needed by the device.
Hints: (a) Suppose that the power is used only to generate the kinetic energy of the water in the jet; and (b) in a time interval of ?t, the amount of mass which flows out the nozzle is ?m, and the corresponding amount of kinetic energy is (?mV2/2).
