PW Class 6 Science Notes Chapter 5: Measurement of Length and Motion

Measuring length may seem simple, but getting a reliable measurement depends on using the right unit and method. In ancient times, people used parts of their bodies such as the foot, hand span, and thumb, but these could give different results for different people. This made it important to develop standard units and clear methods for measuring length.

 Understanding the chapter becomes easier when you connect each measurement concept with its practical use. Physics  Wallah notes cover the non-standard units used in earlier times, the SI system and common length conversions, the limits of non-standard measurements, the correct way to measure an object, and the concepts of distance and reference point.

How Did People Measure Length in Ancient Times?

In ancient times, people used parts of their bodies to measure length, such as the length of their foot, stride, hand span, and thumb. These were not standard units because the measurements varied from person to person. Objects with ruled markings, such as one excavated from the Harappan civilisation, were believed to have been used as scales.

What Are Standard Units of Length?

Suppose a boy measures the length of a table and finds it to be 13 angula. In this measurement, 13 is the number and angula is the unit of measurement.

In ancient times, different units were used to measure length. The system of units used today is known as the International System of Units, or SI units.

The SI unit of length is the metre, written with the symbol m.

Other commonly used units of length include:

• Kilometre (km)

• Centimetre (cm)

• Millimetre (mm)

How Are Units of Length Converted?

The commonly used units of length have the following values:

What Are Disadvantages of Non-Standard Units?

Non-standard units of measurement are not suitable because:

• They lack uniformity.

• They can create confusion.

The variation in measurements from person to person makes it difficult to obtain a consistent result.

What Is the Correct Way to Measure Length?

To measure the length of an object correctly, follow these steps:

1. Place the scale along the length of the object. The zero mark should be aligned with one end of the object.

2. Look directly above the point where the other end of the object meets the scale.

3. Note down the number with units.

Note

For curved lines or objects, length can be measured using a tape or thread. The thread or tape can then be straightened and its length measured using a metre scale.

How Is Distance Measured?

How far one location is from another is measured in terms of distance.

Reference Point

The point from which all distances are measured is known as the reference point.

How Do We Describe Objects in Motion?

If the distance of a body is changing with respect to a reference point, the body is said to be in motion. If the position of a body is not changing with respect to a reference point, it is said to be at rest.

• Linear Motion: When a body moves along a straight line, the motion is called linear motion.

• Circular Motion: When a body moves along a circular path, the motion is called circular motion.

• Oscillatory Motion: When an object moves to and fro about some fixed position, its motion is called oscillatory motion.

 Access Measurement of Length and Motion Chapter 5 Notes PDF

The Physics Wallah Class 6 Science Notes PDF brings the chapter’s important measurement concepts together, making it easier to revisit them during your study and revision.

What Can You Revise with Physics Wallah Notes for Measurement of Length and Motion?

Physics Wallah notes help you quickly revisit the specific concepts covered in this chapter.

• Ancient measurements: Recall the body-based measurements used in ancient times and the non-standard units such as Saan, Muzham, Kaaladi, and Thappadi.

• Standard units: Revisit the meaning of number and unit, SI units, and the metre as the SI unit of length.

• Unit conversion: Refresh the values of millimetre, centimetre, decimetre, decametre, hectometre, and kilometre.

• Measurement method: Remember the correct steps for placing the scale, reading the measurement, and recording the number with its unit.

• Curved lengths: Revisit how thread or tape can be used before measuring the straightened length with a metre scale.

• Distance: Recall the meaning of distance and the role of a reference point.

The chapter takes you through the development of measurement, from using body parts in ancient times to using standard units for greater consistency. It also introduces the correct method of measuring length, along with the concepts of distance and a reference point. Revising these concepts can help you build a clear understanding of the chapter.

Related Resources 

• CBSE Class 6 Science NCERT Solutions 

• CBSE Class 6 Science Sample Paper 

• CBSE Class 6 Science Most Important Questions