How do the tension of the cord and the force of gravity affect a pendulum?

A. They are the competing forces that act on a pendulum as it swings.

B. They are the two factors that affect the period of a pendulum.

C. They determine what type of pendulum it will be.

D. They have no effect on a pendulum.

A. They are the competing forces that act on a pendulum as it swings.

Force of gravity may not affect a pendulum during its equilibrium state. But the gravity can affect the pendulum when a force occurs in any direction of the bob connected to the cord that makes a swing sideways. The gravity of pendulum never stops, it always accelerates. So the gravity affects the pendulum acceleration and speed.

Similarly the tension in the cord will not affect the pendulum but if change in the length of the pendulum while keeping other factors constant changes the length of the period of pendulum. longer pendulum swings with lower frequency than shorter pendulums.