The 5kg slider B can move freely on the smooth vertical pole

The 5-kg slider B can move freely on the smooth vertical pole. Each thin rod of the system has a mass per unit length of 10 kg/m. The system is initially at rest when theta = 60 degree. A constant couple moment M=50 N-m is applied to the rod AB. Determine the velocity of the slider B when theta = 30 degree.

Solution

When the system is in initial position, the rod’s weight, slider and wheel has a positive potential energy. Thus,

Wheel weight + Slider Weight + Road weight (10kg/m x 2 m = 20 kg) = 30 kg = 30 x 9.81 = 294.3 N

y1 = L/2sinQ1

V1 = Wy1 = 294.3 x 1(sin60) = 254.87 J

When the system is in second position,

y2 = L/2sinQ2

V2 = Wy2 = 294.3 x 1(sin30) = 147.15 J