A plank AB 3.0 m long weighing 20 kg and with its centre of gravity 2.0 m from the end A
carries a load of mass 10 kg at the end 4. It
rests on two supports at C and D as shown in
RA
B В
4
50 cm
50 cm
(1) Compute the values of the reaction
forces R; and R, at Cand D.
How far from D. and on which side of it,
must a mass of 24 kg be placed on the
plank so as to make the reactions equal?
What are their values?
(m) Without this 24 kg, what vertical force
applied at B will just lift the plank clear 30
of D? What is then the reaction at C?​