Ps13a33 - Ph 111.01 December 1 2008 PS 13a(33 Problem 1 = Walker P 15-41 To water the yard you use a hose with a diameter of 3.9 cm Water flows

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Ph 111.01 December 1, 2008 PS 13a (33) Problem 1 = Walker P. 15-41. To water the yard, you use a hose with a diameter of 3.9 cm. Water flows from the hose with a speed of 1.2 m/s. If you partially block the end of the hose so the effective diameter is now 0.55 cm, with what speed does water spray from the hose? m/s d 1 d 2 v 1 v 2 A 1 A 2 Solution. The equation of continuity, expressing the fact that the flow rate has to be the same in both sections of the hose, says 11 2 2 Av = Using 2 4 A d π = and solving for v 2 gives () ( ) 2 21 1 2 22 3.9 cm 1.2 m/s 60.3 m/s 0.55 cm Ad vv v === = Problem 2 = Walker P. 15-43. To fill a child's inflatable wading pool you use a garden hose with a diameter of 2.8 cm. Water flows from this hose with a speed of 1.1 m/s. How long will it take to fill the pool to a depth of 21 cm if it is circular and has a diameter of 2.5 m? min d v A D Solution. The flow rate from the hose is h V 2 4 d FA v v == and the flow rate times the unknown time has to equal the volume of the wading pool: 44 Dd Vh F t ππ = v t We set the second and fourth terms equal and cancel the factor of 4 : Dh dv t = and solve for t : 2 2 2.5 m 0.21 m 1 min 1521 s 25.4 min 0.028 m 1.1 m/s 60 s Dh t dv ⎛⎞ = = ⎜⎟ ⎝⎠ Problem 3 = Walker P. 15-53. A garden hose is attached to a water faucet on one end and a spray nozzle on the other end. The water faucet is turned on, but the nozzle is turned off so that no water flows through the hose. The hose lies horizontally on the ground, and a stream of water sprays
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vertically out of a small leak to a height of 0.83 m. What is the pressure inside the hose? kPa Solution. We are going to apply Bernoulli’s law, which sets equal a total energy density, including pressure, at different points along a streamline of flow. In the diagram we show a
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This note was uploaded on 05/13/2010 for the course PHYSICS 111 taught by Professor Staff during the Fall '08 term at S.F. State.

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Ps13a33 - Ph 111.01 December 1 2008 PS 13a(33 Problem 1 = Walker P 15-41 To water the yard you use a hose with a diameter of 3.9 cm Water flows

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