Two hoses have been connected together. The first hose has a diameter of 4 cm, and the second has a diameter of $2.5\mathrm{cm}.$ If the water exits the narrower hose at a speed of $3.4\text{ m/s}$, how quickly is the water moving inside the wider hose?

(II) Estimate the air pressure inside a category 5 hurricane, where the wind speed is 300 km/h (Fig. 13–56).

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(II) A viscometer consists of two concentric cylinders, 10.20 cm and 10.60 cm in diameter. A liquid fills the space between them to a depth of 15.0 cm. The outer cylinder is fixed, and a torque of 0.024 m · N keeps the inner cylinder turning at a steady rotational speed of 57 rev/min. What is the viscosity of the liquid?

(I) Engine oil (assume SAE 10, Table 13–3) passes through a fine 1.80-mm-diameter tube that is 10.2 cm long. What pressure difference is needed to maintain a flow rate of 5.8 mL/min?

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(II) Poiseuille’s equation does not hold if the flow velocity is high enough that turbulence sets in. The onset of turbulence occurs when the Reynolds number, Re, exceeds approximately 2000. Re is defined as

Re = 2υ¯rρ /η ,

where υ¯ is the average speed of the fluid, ρ is its density, is its viscosity, and r is the radius of the tube in which the fluid is flowing.

(a) Determine if blood flow through the aorta is laminar or turbulent when the average speed of blood in the aorta ( r = 1.2 cm) during the resting part of the heart’s cycle is about 35 cm/s.