State the condition when a body is in (i)   static equilibrium. (ii)  dynamic equilibrium. Give one example each of static and dynamic equilibrium.

Static equilibrium : When a body remains in the state of rest under the influence of several forces, the body is said to be in static equilibrium.
Example :
(a) A book lying on a table
(b) Beam balance in horizontal balance

Dynamic equilibrium : When a body remains in the same state of motion under the influence of several forces, the body is said to be in dynamic equilibrium.
Example :
(a) A rain drop reaches the earth surface with a constant velocity.
(b) Aeroplane moves at the constant height
(c) Stone tied at the end of the string
(d) Revolution of moon around the earth