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SAI International School
Class VII
Lesson Notes
Subject: Physics
Ch-Time and Motion
Subtopic: Simple Pendulum

Simple Pendulum:

Periodic motion is the motion which repeats itself in fixed interval of time. The principle of
periodic motion is used in making clocks and watches.

 Astronomer Galileo Galilei, performed experiments to measure time using Simple Pendulum.
 Further, it helped to develop a time-measuring device called the Pendulum clock.

Construction:

Simple Pendulum consists of small metallic bob tied to a non stretchable string and suspended
from a fixed point. The bob is made to swing in the to and fro direction.

Terms Associated with motion of pendulum:

1. Mean position: The rest position of bob is known as mean position.(Position A)
2. Extreme position:Extreme position is the position of the bob at the maximum distance
from the mean position.(Position B and C)
3. One Oscillation: The one complete cycle of swinging from one extreme to other
extreme and then returning to its original starting position.
4. Amplitude: It is defined as the maximum displacement of a pendulum from its mean
position.(displacement AB and AC)
5. Time period: The time taken by the pendulum to complete one oscillation is called time
period.