A conical tank has height 3 m and radius 2 m at the top. Water flows in at a rate of 1.5 m3/min. How fast is the water level rising when it is 1.1 m from the bottom of the tank? (Round your answer to three decimal places.)

Respuesta :

Explanation:

It is known that general formula to calculate the volume of a cone is as follows.

       Volume of the cone = [tex]\frac{1}{3} \pi r^{2}h[/tex]

and here, r = [tex]\frac{2}{3}h[/tex]  

So,    V = [tex]\frac{1}{3} \pi \times (\frac{4}{9}) \times (h^{3})[/tex]

On putting the given values into the above formula we will calculate the value f h as follows.

        V = [tex]\frac{1}{3} \pi \times (\frac{4}{9}) \times (h^{3})[/tex]

           = [tex]\frac{1}{3} \times \pi \times (\frac{4}{9}) \times (h^{3})[/tex]

           = [tex]\frac{4 \pi}{27} h^{3}[/tex]

Now, we will differentiate w.r.t t as follows.

        [tex]\frac{dV}{dt} = \frac{d}{dt}(\frac{4 \pi}{27}h^{3})[/tex]

                     = [tex]\frac{4\pi}{27}(3h^{2}) \frac{dh}{dt}[/tex]

It is given that water here flows at a rate of 1.5 [tex]m^{3}/min[/tex] and h = 1.1 m.

      [tex]\frac{dV}{dt} = \frac{4 \pi}{27}(3h^{2}) \frac{dh}{dt}[/tex]

            1.5 = [tex]\frac{4 \pi}{27}(3h^{2})\frac{dh}{dt}[/tex]

            1.5 = [tex]\frac{4 \pi}{27}(3(1.1)^{2})\frac{dh}{dt}[/tex]    

             [tex]\frac{dh}{dt}[/tex] = 0.888

                             = 0.9 m/min (approx)

Thus, we can conclude that the water level is rising at a rate of 0.9 m/min.