The pendulum of a wall clock executes an oscillatory motion.

Oscillatory motion refers to the repetitive back and forth motion of an object around a stable equilibrium position. It is characterized by the object moving to one side of the equilibrium position, then moving back to the other side, and repeating this motion in a regular pattern.

The motion of a pendulum can be described as an oscillatory motion because it follows this repetitive pattern. The pendulum consists of a weight called the bob, which is attached to a fixed point by a string or rod. When the pendulum is displaced from its equilibrium position and released, it swings freely back and forth.

Key Points:
- The pendulum of a wall clock consists of a bob attached to a fixed point.
- The pendulum is displaced from its equilibrium position and released.
- The pendulum swings freely back and forth in a regular pattern.

The motion of the pendulum can be further explained by the concept of periodic motion. Periodic motion is a type of oscillatory motion that repeats itself after a fixed interval of time. In the case of a pendulum, the time taken for one complete back and forth swing, known as the time period, remains constant as long as the length of the pendulum and the acceleration due to gravity remain constant.

The motion of the pendulum is governed by the principles of simple harmonic motion (SHM). SHM is a type of oscillatory motion in which the restoring force is directly proportional to the displacement of the object from its equilibrium position and acts in the opposite direction. In the case of a pendulum, the restoring force is provided by gravity, which acts to bring the pendulum back towards its equilibrium position as it swings.

Key Points:
- The motion of the pendulum follows the principles of simple harmonic motion.
- Simple harmonic motion involves a restoring force that is proportional to the displacement.
- Gravity provides the restoring force for the pendulum.

In conclusion, the pendulum of a wall clock executes an oscillatory motion because it follows a regular back and forth swinging pattern, with a fixed time period and a restoring force provided by gravity.