Question

describe the necessary requirement(s) for an object to be in static and dynamic equilibrium.
multiple choice
the object should be subjected to a zero net force but can accelerate in a rotational manner.
the object can be moving at any speed in any direction as long as its angular acceleration is zero.
the object must be moving with constant acceleration.
both the net force and the net torque acting on it must equal zero.

Explanation:

For static/dynamic equilibrium, net force ($\sum F = 0$) and net torque ($\sum \tau = 0$) must be zero. 1st option: Rotational acceleration means net torque ≠ 0, invalid. 2nd: Angular acceleration zero doesn't ensure net force zero. 3rd: Constant acceleration means net force ≠ 0, invalid. 4th matches the requirements.

Answer:

D. Both the net force and the net torque acting on it must equal zero.