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•• Unfiltered olive oil must flow at a minimum speed of 3.0 m/s to prevent settling of debris in a pipe. The oil leaves a pump at a pressure of 88 kPa through a pipe of radius 9.5 mm. It then enters a horizontal pipe at atmospheric pressure. Ignore the effects of viscosity. (a) What is the speed of the oil as it leaves the pump if it flows at 3.0 m/s in the horizontal pipe? (b) What is the radius of the horizontal pipe?

Respuesta :

Answer:

a

The velocity at which the oil leaves the pump is [tex]v_1 = 5.15 m/s[/tex]

b

The radius of the horizontal pipe  [tex]r_2 = 0.01244 m[/tex]

Explanation:

From the question we are told that

    The rate of flow of unfiltered olive oil is  [tex]v = 3.0 m/s[/tex]

    The pressure on the pump is [tex]P_1 = 88 kPa = 88 *10^{3} \ Pa[/tex]

     The radius of the pipe is  [tex]r = 9.5 = \frac{9.5}{1000} = 0.0095 \ m[/tex]

     

Generally we can define this motion with Bernoulli's Equation as

       [tex]P_1 + \frac{1}{2} \rho v_1 ^2 + \rho g h_1 = P_2 + \frac{1}{2} \rho v_2 + \rho g h_2[/tex]

          [tex]P_2[/tex]  is the  pressure inside the pipe which is the atmospheric pressure which has a value of [tex]P_2 = 1.01 *10^{5} \ Pa[/tex]

           [tex]\rho[/tex] is the density of olive oil which has a value of [tex]\rho = 980 kg/m^3[/tex]

           [tex]g[/tex] is the acceleration due to gravity

           h the height of the pipe since from the question we are not told that it is place on anything hence the height is the diameter of the pipe

           [tex]v_1 \ and \ v_2[/tex] are the speed at which it leaves the pump and the speed at which it flows in the pipe respectively

Making [tex]v_2[/tex]  the subject of the equation

              [tex]v_1 = \sqrt{[\frac{2}{\rho} (P_2 -P_1 - \frac{1}{2} v^2_2)]}[/tex]

Substituting values

              [tex]v_1 = \sqrt{[\frac{2}{980} (1.01 *10^5 -88 *10^{3} - \frac{1}{2}(3.0)^2)]}[/tex]

              [tex]v_1 = 5.15 m/s[/tex]

Using continuity equation to define the motion of this fluid we have

              [tex]A_1 v_1 = A_2 v_2[/tex]

Where  [tex]A_1[/tex] is the area of the pump which is circular so mathematically it is

        [tex]A_1 = \pi r^2_1[/tex]

         [tex]A_2[/tex] is the area of the horizontal pipe  which is circular so mathematically it is

            [tex]A_2 = \pi r^2_2[/tex]

So the continuity equation becomes

             [tex]\pi r^2 _1 v_1 = \pi r^2 _2 v_2[/tex]

Making [tex]r_2[/tex] subject of formula

            [tex]r_2 = \sqrt{\frac{r_1^2 v_1}{v_2} }[/tex]

Substituting values

           [tex]r_2 = \sqrt{\frac{ 0.0095^2 5.15 }{3.0} }[/tex]

           [tex]r_2 = 0.01244 m[/tex]

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