An ideal pendulum is often discussed when studying simple harmonic motion.

What are the conditions needed for an ideal pendulum? Check all that apply.

A) Gravitational force acts to pull the pendulum's mass down.

B) The mass of the rod of the pendulum is evenly distributed along the rod.

C) The pivot on which the pendulum swings is frictionless.

D) The pendulum swings through its equilibrium position as a result of inertia.

E) Tension acts downward on the pendulum's mass.

So lets see what are the conditions for a simple pendulum:

The gravitational force acts in the downward direction on a pendulums mass so A) is the correct condition.

An ideal simple pendulum has a massless wire or a mass that we can neglect so B) isn't a correct condition.

If there were some friction in the pivot then the force of friction would eventually stop the pendulum and motion of the pendulum wouldn't be simple harmonic motion so C) is a correct condition.

Gravity is the restoring force that moves the pendulum towards its equilibrium position, not inertia so D) isn't the correct condition.

Direction of the tension is not downwards because tension is the force that acts on the mass to cause circular motion of the pendulum. It's direction is towards the pivot. So E) isn't the correct condition.

So A) and C) are the correct conditions for simple pendulum.