Problem 8 If both men in the figure below pull on their rope

Problem 8. If both men in the figure below pull on their ropes with a force of 30 lb (P F 30 lb), which direction will the pole rotate about point A. 6 it 45° 12 ft a) The system is in equilibrium and the pole will not rotate (b) Clockwise (c) Counter-clockwise

Solution

Find the moment about A due to P and F. If moment is zero then it is in equilibrium. Otherwise not.

M_A = P*cos(45)*18 - F*(4/5)*12

=30*cos(45)*18 - 30 * 48/5

=381.83 -288

=93.83 lb.ft.

Hence this will rotate in anti clockwise direction ( couple due to P is more)