Science Curiosity Notes Class 6 English Medium 2026-27

Science Curiosity Chapter 5. Measurement of Length and Motion

CBSE Notes New Syllabus: Class 6

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Chapter 5. Measurement of Length and Motion

Measurement is an essential part of our daily life. We measure the length of objects, the distance between places, and the movement of different objects around us. Accurate measurement helps us perform scientific experiments, construct buildings, manufacture machines, play sports, and carry out many everyday activities. This chapter explains the importance of standard units of measurement, different measuring instruments, correct methods of measuring length, reference points, and various types of motion.

CBSE Notes - Key Points

The following notes provide important definitions, scientific terms, formulas, and key facts from the chapter. These notes are useful for quick revision before school examinations and CBSE assessments.

Important Keywords

• Measurement
• Length
• SI Unit
• Metre (m)
• Centimetre (cm)
• Millimetre (mm)
• Kilometre (km)
• Reference Point
• Rest
• Motion
• Linear Motion
• Circular Motion
• Oscillatory Motion
• Periodic Motion
• Parallax Error
• Measuring Tape
• Metre Scale
• Ruler
• Standard Unit
• Ancient Units

Important Definitions

Measurement: The process of finding the length, distance, or size of an object by comparing it with a standard unit.

Length: The distance between two ends of an object.

SI Unit: The internationally accepted standard unit used for scientific measurements.

Metre: The SI unit of length represented by the symbol m.

Reference Point: A fixed object or place used to describe the position or motion of another object.

Rest: A body is said to be at rest if its position does not change with time with respect to a reference point.

Motion: A body is said to be in motion if its position changes with time with respect to a reference point.

Linear Motion: Motion of an object along a straight path.

Circular Motion: Motion of an object along a circular path around a fixed point.

Oscillatory Motion: The repeated to-and-fro motion of an object about its mean position.

Periodic Motion: Motion that repeats itself after equal intervals of time.

Parallax Error: The error caused when a scale is read from an angle instead of vertically above the marking.

Important Unit Conversions

Measuring Instruments

Important Facts

• The SI unit of length is the metre.
• Standard units are accepted throughout the world.
• Body-part measurements are not reliable because they differ from person to person.
• A ruler should always be placed exactly along the object being measured.
• The eye should be kept vertically above the scale to avoid parallax error.
• A damaged ruler can still be used by taking the difference between two readings.
• Curved lengths are measured using a thread or measuring tape.
• Every position is described with respect to a reference point.
• Motion depends on the selected reference point.
• Linear motion takes place in a straight line.
• Circular motion takes place along a circular path.
• Oscillatory motion is a repeated to-and-fro movement.
• Periodic motion repeats after equal intervals of time.
• The Earth rotates about its axis and revolves around the Sun.
• Ancient India used units such as Angula, Dhanusa, and Yojana for measurement.

Quick Revision

• Measurement helps us compare objects accurately.
• The SI unit of length is metre (m).
• 1 km = 1000 m.
• 1 m = 100 cm.
• 1 cm = 10 mm.
• Use the correct measuring instrument according to the object.
• Always avoid parallax error while taking readings.
• A reference point helps describe the position of an object.
• An object is at rest if its position does not change.
• An object is in motion if its position changes with time.
• Linear, circular, and oscillatory are the three main types of motion.
• Periodic motion repeats after equal intervals of time.
• Standard units provide accurate and uniform measurements.