IVB. (17 pts) As shown in the figure, the uniform plank has a length 4.2 m and a weight 110 N. A block of unknown weight rests on the right end of the plank. A man's two hands hold the plank horizontal. The == force by his right-hand FR = 250 N. Refer to the figure for other relevant parameters. Find the magnitude of the force FL (by the man's left-hand), and the weight of the block Whinck. (In your calculations, before calculating any torque, clearly mark your choice of rotational axis on the drawing) 4.2m 1.1m FL = ? 0.2m F CG FR=250N W plank 110N Wblock = ?