Question

A cylindrical tank with length 5 ft and raduis of 3 ft is situated wit its axis horizontal. if a circular bottom hole with a radius of 1 in. is opened and the tank is initially half full of xylene, how long will it ake for the liquid to drain completely? PLEASE HELP

Answer 1

Start with Bernoulli's equation which relates dV/dt to pressure. Yes, you will have to know density of xylene. http://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html

Answer 2

This didn't help me much bobpursley, I am just so confused.

Answer 3

Write an equation (based on Bernoulli's equation) for the volume flow rate in terms of the height of the water in the tank, which is proportional to pressure. That height y will be a function of the remaining volume, V.

Derive the equation dV/dt = f{y(V)}
where y is the height of water in the tank. To get the time to empty the tank, solve by separation of variables.

Integral of t = Integral of dV/f(V)

dV/dt = -(hole area)*(liquid velocity at opening)
liquid velocity at opening= sqrt(2gy)

it appears that the liquid density cancels out. You will need to express y in terms of V to do the integration. The integration might be messy. That is as far as I am going with this.