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CBSE Class 7 Physics Notes- Chapter 3 Motion and Time

CHAPTER 3 MOTION AND TIME

SPEED
Speed of an object determines how fast or slow the object is moving. Speed is total distance divided by time taken to cover the
distance.

Speed= Total Distance / Time

We use devices like clocks to measure time. Clocks work on a simple concept of periodic motion. Simple pendulum is the most common object to exhibit periodic motion.
Simple pendulum
A simple pendulum consists of a small metallic ball (called a bob) suspended by a thread.
The pendulum has an oscillatory motion. The time taken by the pendulum to complete one oscillation is called its time period. The time period of the pendulum increases with an increase in the length of the string from which it is suspended.

DISTANCE-TIME GRAPHS
A graph between the distance travelled by an object and the time is called a distance- time graph.
For an object travelling with uniform speed, the distance-time graph is a straight line.