Solving Diff Eq for Free-fall w/o Drag in Tank Outlet

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This discussion focuses on solving differential equations related to the free-fall velocity of liquid draining from a tank outlet without drag. The key equation derived is v = sqrt(2gh), where v represents the velocity of the liquid, g is the acceleration due to gravity (9.81 m/s²), and h is the height of the liquid above the outlet. The user seeks assistance in deriving the function h(t) that describes the height of the liquid over time, given the parameters of a right circular cylinder tank with specific dimensions and a contraction coefficient. The problem emphasizes the relationship between the rate of outflow and the rate of change of liquid height in the tank.

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  • Understanding of differential equations
  • Knowledge of fluid dynamics principles
  • Familiarity with the concepts of cross-sectional area and flow rates
  • Basic physics of gravity and free-fall motion
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  • Study the derivation of differential equations in fluid dynamics
  • Learn about the application of Bernoulli's principle in fluid flow
  • Explore the method of separation of variables for solving differential equations
  • Investigate the effects of contraction coefficients on fluid flow rates
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This discussion is beneficial for physics students, engineers, and anyone interested in fluid mechanics and the mathematical modeling of liquid dynamics in tanks.

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Suppose a tank containing a liquid has an outlet near the bottom. The velocity of the liquid flowing out of the outlet is equal to a particle free falling without drag.

a. show that v=sqrt(2gh)

b. by finding the rate of outflow to the rate of change of the liquid in the
tank, find h(t) that satisfies the equation:
A(h)(dh/dt) = (-b)(a)(sqrt(2gh))

A(h) = the area of the cross section of the tank at height h
b = a contraction coefficient that describes how the water flows (constant)
a = the radius of the outlet
g = gravity (9.81 m/s^2)

c. Consider a water tank in the form of a right circular cylinder. The water level is 3m above the outlet. Radius of tank is 1m radius of outlet is 0.1m. the value for the constant "b" is 0.6 How long does it take to drain the tank to the level of the outlet.

I have solved part a and really need help for the rest. If anyone can help it would be greatly appreciated. Also if you don't mind doing part A i would like to check my method.
 
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Hi and welcome to Physicsforums he lives.
Before we help, we need to see some effort on your side. Can you post your attempt at this problem, along with your thoughts or ideas on how to solve it?
 

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