$A$ box of mass $m$ is in equilibrium under the application of three forces as shown below. If the magnitude of $F_1$ is $10 \ N$,what is the magnitude of $F_3$ (in $N$)?

If more than one force acts on a particle,state the condition for the equilibrium of the particle.

$A$ body of mass $60\,kg$ is suspended by means of three strings $P, Q$ and $R$ as shown in the figure. The system is in equilibrium. The tension in the string $P$ is $..........\,N$. (Take $g = 10\,m/s^2$)

Which of the following sets of three forces acting on a body cannot have a resultant of zero?

The adjoining figure shows a force of $40\, N$ acting at $30^o$ to the horizontal on a body of mass $5\, kg$ resting on a smooth horizontal surface. Assuming that the acceleration due to gravity is $10\, ms^{-2}$,which of the following statements is (are) correct?
$[1]$ The horizontal component of the applied force is $20\sqrt{3}\, N$.
$[2]$ The weight of the $5\, kg$ mass acts vertically downwards.
$[3]$ The net vertical force acting on the body is $30\, N$ (upwards).

$A$ small sphere is hung by a string fixed to a wall as shown in the figure. The sphere is pushed from the wall by a stick. The forces acting on the sphere are as shown. Then,identify the incorrect expression.