$A$ horizontal force $F$ is applied to a block as shown in the figure such that the block remains in a state of rest. Which of the following statements is true?

$A$ heavy iron bar of weight $W$ has one end on the ground and the other on the shoulder of a person. The bar makes an angle $\theta$ with the horizontal. The weight experienced by the person is:

$A$ 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

$A$ metre stick is balanced on a knife edge at its centre. When four coins, each of mass $2 \,g$, are placed one on top of the other at the $10.0 \,cm$ mark, the stick is found to be balanced at the $46.0 \,cm$ mark. The mass of the metre stick is: (in $\,g$)

Persons $A$ and $B$ are standing on the opposite sides of a $3.5 \,m$ wide water stream which they wish to cross. Each one of them has a rigid wooden plank whose mass can be neglected. However,each plank is only slightly longer than $3 \,m$. So,they decide to arrange them together as shown in the figure. With $B$ (mass $17 \,kg$) standing on one end of the plank,the maximum mass of $A$,who can walk over the plank is close to ............ $kg$.

If torque is calculated relative to a reference point and this point is displaced,does the condition for rotation remain valid?