Meriam, Kraige & Bolton — Kinetics of Particles: Problem 3_44

3/44 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 \(\dot{\theta} = 3 \text{ rad/sec}\). If a 0.2-lb particle is sliding in the tube toward O with a velocity of 6 ft/sec relative to the tube when the position \(\theta = 30^\circ\) is passed, calculate the magnitude \(N\) of the normal force exerted by the wall of the tube on the particle at this instant.