Bernoulli's Principle and water tank

[mad_monkey_j]

Homework Statement

A sealed tank is completely full of water. The water in the tank is stationary. The gauge pressure at the top of the tank is 150 kPa.
A mechanical failure of the tank creates a hole of area 1.00 cm2 at the top of the tank. Water flows out of the hole, rising in a vertical column.

What is the speed of the water as it emerges from the hole?

What is the height of the column of water?

Homework Equations

P+1/2*rho*v^2+rho*gy=constant
v=(2gh)^1/2

The Attempt at a Solution

I calculated the abs pressure as 251.3k Pa
But then i don't know how to find the speed without the height of the water?

 

[nayfie]

Considering the tank is completely full of water, I think the gauge pressure would be the absolute pressure?

Anyway;

$$P =\rho gh$$

You know what the pressure at the top of the tank is, you know what the density of water is, and you know what gravity is.

:)

 

[mad_monkey_j]

Did not think of using that equation at all, thanks.

 

[nayfie]

No worries. On second thought though, they specifically say gauge pressure, so you were probably right on the absolute pressure you calculated before.

 

[mad_monkey_j]

Yeah the absolute pressure I calculated was right.