Question

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

• A. $\frac{W(d-x)}{x}$
• B. $\frac{W(d-x)}{d}$
• C. $\frac{Wx}{d}$
• D. $\frac{Wd}{x}$

Answer 1

Answer: (B)

$\frac{W(d-x)}{d}$

Taking moment about point B
$N_{A}d-W(d-x)=0$
$N_A=\frac{W(d-x)}{d}$
hence correct answer is option B.