To lift the rod?

Question

A rod being used as a lever is shown in the figure below . The fulcrum is 1.2 m from the load and 2.4 m from the applied force. If the load has a mass of 20.0 kg, what force must be applied to lift the load?

http://i116.photobucket.com/albums/o23/dead10252006/4.gif

Answer 1

The CCW torque of the load on the lever is the weight of the load times the distance or 20 kg*g*1.2 m. The applied force needs to apply an equal CW torque to balance the load: F*2.4 m. So

20 kg*g*1.2 m = F*2.4 m
F = 20 kg*g*1.2 m / 2.4 m

F will just balance the load. To lift it, you need a bit more force - give it about 1/2 a microNewton more