A non-uniform rod XY of mass 40 kg and length 5.0 m lines on the horizontal ground. Its centre of gravity is 2.0 metres from the end X .Calculate the vertical Force P that will just be sufficient to lift the end Y from the ground. Why would the force P, is applied at the end X not be sufficient to lift the end X from the ground? (g=10.0 ms^-2)

-a plank XY 3.0m long weighing 20 kg and with its centre of gravity 2.0m from the end A carries a load mass 10 kg at the end A. It rests on two support at C and D.

a)Compute the values of the reaction forces R1 R2 at C and D.

b) How far from D ,and on which side of it must the mass of 24 kg placed on the plank so as to make the reactions equal ? ,What are their values.

c)Without this 24kg ,what vertical Force applied at we will just leave the plank clear of D? What is then the reaction at C?