The hollow tube is pivoted about a horizontal axis through point O and is made to rotate...

The hollow tube is pivoted about a horizontal axis through point O and is made to rotate in the vertical plane with a constant counterclockwise angular velocity rad/sec. If a 0.2-lb particle is sliding in the tube toward O with a velocity of 4 ft/sec relative to the tube when the position θ = 30^o is passed, calculate the magnitude N of the normal force exerted by the wall of the tube on the particle at this instant.