# Measurement of Distance, Motion, Types of Motion, Methods of Measurement (For CBSE, ICSE, IAS, NET, NRA 2022)

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# Measurement of Distance, Motion, Types of Motion

## Measurement

• Measurement is the comparison of an unknown quantity with a known fixed quantity It basically consists of two things:
• Units: The known fixed quantity used for measurement is termed as unit.
• Number: The number of units an object contains.

### Methods of Measurement

From past decades, people have been inquisitive about measuring the distance. They developed many ways for measuring.

### Conventional System of Measurements

• This method predicts the approximate measure of an object.
• One of the biggest disadvantages of this method is it varies from person to person.
• Some common units used in such kind of measurement include,

### Standard System of Measurements

• This system includes standard units of measurement.
• This units are consistent and do not vary from person to person.
• This system of units now is better known as International System of units (SI unit) .
• SI unit of distance is meter (m) .

### Points to Remember While Taking Measurements

• Select right measurement device for taking any measurement.
• Place the initial point accordingly with the value on scale equal to 0. Place the scale along the length you are measuring.
• In some scales you may be unable to see the zero mark select the initial and final notations on scale.

Make sure your eye is exactly in front of the scale reading. Correct position of eye is also important. You can obtain different value for different positioning of your eye as per the scale.

## Motion of Bodies

A body is said to be in motion if it changes its position over a period of time.

### Types of Motion

• Rectilinear motion: The Rectilinear motion in a straight line is termed as rectilinear motion. For example: motion of sprinters in a race, march past of soldiers in a parade etc.
• Circular motion: Circular Motion of objects such that they always remain at a same distance from a fixed point is termed as circular motion. For example, motion of blades of fan. This motion is also termed as the rotational motion if objects execute circular motion on their own axis. For example, blades of wind mill.
• Periodic motion: The Periodic motion in which particle attains its natural position after a fixed interval of time is termed as periodic motion. For example: motion of a pendulum.

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