When is a body said to be in mechanical equilibrium?

Write the condition for the translational equilibrium of a particle.

There are three forces $\vec{F_1}$,$\vec{F_2}$,and $\vec{F_3}$ acting on a body,all acting on a point $P$ on the body. The body is found to move with uniform speed.
$(a)$ Show that the forces are coplanar.
$(b)$ Show that the torque acting on the body about any point due to these three forces is zero.

$A$ body of mass $m$ is suspended by two strings making angles $\theta_1$ and $\theta_2$ with the horizontal ceiling with tensions $T_1$ and $T_2$ respectively. If $T_1 = \sqrt{3} T_2$,then the angles $\theta_1$ and $\theta_2$ are:

$A$ body under the action of several forces will have zero acceleration:

$A$ body of mass $40 \,g$ is moving with a constant velocity of $2 \,cm/s$ on a horizontal frictionless table. The force on the table is ....... $dyne$.