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
\theta ^(?)=3ra(d)/(sec)
. If a
0.2-lb
particle is sliding in the tube toward
O
with a velocity of
6f(t)/(sec)
relative to the tube when the position
\theta =30\deg
is passed, calculate the magnitude
N
of the normal force exerted by the wall of the tube on the particle at this instant.