A rod of weight W is supported by two parallel knife edges A and B and is in equilibrium in a horizontal position. The knives are at a distance d from each other. The centre of mass of the rod is at distance x from A. The normal reaction on A is :
W(d-x) /d
For equilibrium
N1x=N2(d−x) and N1+N2=W
∴N1x=(W−N1)(d−x)
N1x+N1(d−x)=W(d−x)
∴N1=W(d−x)d