如图所示，半径为R的半球形陶罐，固定在可以绕竖直轴旋转的水平转台上，转台转轴与过陶罐球心O的对称轴OO′重合．转台以一定角速度ω匀速旋转，一质量为m的小物块落入陶罐内，经过一段时间后，小物块随陶罐一起转动且相对罐壁静止，它和O点的连线与OO′之间的夹角θ为60°．重力加速度大小为g．

（1）若ω=ω₀，小物块受到的摩擦力恰好为零，求ω₀；

（2）若ω=2

Production of mechanical foam by a portable in-line foam proportioner（）.

A.increases the size of foam bubbles formed

B.increases the rate of foam production

C.improves the extinguishing properties of foam

D.gives the nozzleman more freedom of movement，since it can be placed anywhere in the hose line