CHAPTER 1 MOTION AND MEASUREMENT OF DISTANCES
HISTORY OF TRANSPORTATION
Back in the day when there were no vehicles, people had to walk on foot or use animals for transportation. To travel across the water bodies, boats were used.
With the invention of the wheel, transportation became easier. Animals were used to pull the vehicles. These vehicles moved on wheels.
Then came the steam engine. It made long distance transportation easier.
MEASUREMENT OF LENGTH-DISTANCE
People used strings in order to measure lengths. They also used the length of foot as a standard measurement of length. That’s where the term ‘foot’ comes from.
A ‘hand span’ was also used. A ‘span’ is the distance between the tip of the thumb and the tip of the little finger when the hand is fully extended.
The fixed known quantity which is used to measure an unknown quantity is called a ‘unit’.
STANDARD UNITS OF MEASUREMENT
The standard set of units accepted all over the world is the International System of Units
The SI unit of length is a metre.
Other units used for measuring length are centimetre, millimetre, etc.
1 metre= 100 centimetres
1 centimetre= 10 millimetres
1 kilometre= 1000 metres
TYPES OF MOTION
1. Rectilinear motion
If an object moves in a straight line, the motion is called rectilinear motion. E.g.: Motion of a vehicle on a straight road
2. Circular motion
If an object moves in such a way that its distance from a fixed point remains same, the motion is called circular motion. E.g.: Motion of a fan
3. Periodic motion
If an object moves in a way that it repeats its motion after some time, the motion is called periodic motion. E.g.: A swinging pendulum
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