# Rotating Pail of Water

1. Nov 3, 2007

### Fusilli_Jerry89

1. The problem statement, all variables and given/known data
A rotating pail of water with an angular velocity w has a surface curving up from the centre to the outer edge. Find the shape of the surface. The slope of the surface is dy/dx = tan(theta) at position x is y (= function of x) is the shape of the surface. You must resolve forces to find tan(theta) as a function of x, and then solve for the height, y, as a function of x.

If the pail rotates once per second, and has a diameter of 0.45 m, how high above the centre is the outer edge?

2. Relevant equations

3. The attempt at a solution
All I see is that w = 2pi rad/sec and r = 0.225 m.

2. Nov 4, 2007

### saket

Method I:
Ideal Fluid, by definition, can not tolerate any shear force. Use this fact.
Assume the centre of the water surface to be origin. Let P(x,y) be a point on the water surface. Consider forces on it. Impose the condition that tangential force will be zero.
I hope you can proceed now.