What is the minimum number of forces acting in the same plane on a particle that can result in a zero net force?

The $50\,kg$ homogeneous smooth sphere rests on the $30^{\circ}$ incline $A$ and bears against the smooth vertical wall $B$. Calculate the contact forces at $A$ and $B$.

$A$ book of mass $5 \,kg$ is placed on a table and it is pressed by $10 \,N$ force. Then,the normal force exerted by the table on the book is ......... $N$.

Three forces acting on a body are shown in the figure. To have the resultant force only along the $y$-direction,the magnitude of the minimum additional force needed is:

$A$ small child tries to move a large rubber toy placed on the ground. The toy does not move but gets deformed under her pushing force $F$,which is obliquely upward as shown in the figure. Then,

$A$ flexible chain of mass $m$ hangs between two fixed points at the same level. The inclination of the chain with the horizontal at the two points of support is $30^{\circ}$. Considering the equilibrium of each half of the chain, the tension of the chain at the lowest point is . . . . . . .