Aperson carries a plank of wood 2.00 m long with one hand pushing down on it at one end with a force f1 and the other hand holding it up at .500 m from the end of the plank with force f2 . if the plank has a mass of 20.0 kg and its center of gravity is at the middle of the plank, what is the magnitude of the force f1?

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.