1. Clock: Clock can be defined as a device that measures time.
2. Motion: Motion is defined as the change of position of a body with respect to time.
3. Periodic motion: Periodic motion is a motion that reoccurs in fixed intervals of time.
4. Pendulum: A bob with a small mass, suspended freely from a fixed support so that it can swing to and fro under the influence of gravity is called a pendulum.
5. Speed: Speed can be defined as the distance travelled by an object in unit time.
6. Uniform motion: If an object covers equal distances in equal intervals of time, then the object is said to be in uniform motion.