Question

Compare and contrast static and dynamic equilibrium, then give me an example scenario for each of these states of equilibrium.

If your above scenarios only meet the second condition for equilibrium (but not the first), describe what should happen.

Answer 1

If the combined effect of all the forces acting on a body is zero and the body is in the state of rest then    its equilibrium is termed as static equilibrium. An example would be any stationary body

when a body is in state of uniform motion and the resultant of all forces acting upon it is zero then it is    said to be in dynamic equilibrium. Jumping from the sky with the help of a parachute.

There are two conditions to be met for a body to be in equilibrium

a) The vector sum of all the linear forces must be zero

b) vector sum of all the rotational torques (forces) must be zero

If either of this condition is not met, then there may be an increased loading and system may undergo bending and fracture.