NCERT Solutions for Class 6th Science Chapter 5 Measurement of Length and Motion
Updated on 2026-09-19
About this chapter
A measurement always has two parts — a number and a unit . Saying “the table is 13 handspans long” means 13 is the number and handspan is the unit. Body-based units — handspan (balisht), angula, foot, cubit — differ from person to person, so the same table gave 13, 14 and “a little more than 13” to different children. That is why the world agreed on standard units . The system used today is the International System of Units (SI) . The SI unit of length is the metre (m) , and 1 km = 1000 m , 1 m = 100 cm , 1 cm = 10 mm (so 1 m = 1000 mm and 1 km = 1,00,000 cm). Using a scale correctly: keep it in contact with the object and along its length , keep the eye directly above the mark being read, and if the zero end is broken, use any full mark and subtract — for example 10.4 cm − 1.0 cm = 9.4 cm
- Chapter opener
- .1 How do we Measure?
- .2 Standard Units
- .3 Correct Way of Measuring Length
- .4 Measuring the Length of a Curved Line
- .5 Describing Position
- .6 Moving Things
- .7 Types of Motion
- Chapter exercises
- Extended activities and projects
Quick revision
| Term | What it means | Where it comes in the chapter | Example / value |
|---|---|---|---|
| Unit | The fixed length chosen for comparison. A measurement = a number + a unit | Page 81 | “13 handspans”: 13 is the number, handspan is the unit |
| Handspan (balisht) | The distance from the tip of the thumb to the tip of the little finger of a spread-out hand | Fig. 5.1, page 80 | Differs from person to person → not a standard unit |
| Standard unit / SI units | A unit fixed by agreement between countries so that everyone gets the same value. The present system is the International System of Units | Section 5.2, page 82 | SI unit of length = metre (m) |
| metre (m) | The SI unit of length; one metre is divided into 100 equal parts | Page 82 | Height of a door ≈ 2 m |
| centimetre (cm) and millimetre (mm) | One division of a metre scale is 1 cm; one-tenth of a centimetre is 1 mm — the smallest length a 15-cm scale can measure | Pages 82–83 | 1 m = 100 cm; 1 cm = 10 mm; 1 mm = 0.1 cm |
| kilometre (km) | A larger unit used for long distances; 1 km = 1000 m | Page 83 | Delhi to Lucknow ≈ 500 km |
| Reference point | The fixed object or point with respect to which a distance or position is stated | Page 88 | Delhi, written on a kilometre stone |
| Motion and rest | In motion = position changes with time with respect to the reference point; at rest = position does not change | Page 90 | Bus passengers: at rest w.r.t. the bus, in motion w.r.t. a building |
| Linear motion | Motion of an object along a straight line | Page 92 | A heavy box being pushed; march-past in a parade |
| Circular motion | Motion of an object along a circular path | Page 92 | Merry-go-round; a stone whirled on a thread |
| Oscillatory motion | To-and-fro motion of an object about a fixed position | Page 93 | A swing; a plucked metal strip |
| Periodic motion | Motion that repeats itself after a fixed interval of time | More to know!, page 94 | Both circular and oscillatory motion are periodic |
Exercises
- Chapter opener — In-text Questions Page 79
- .1 How do we Measure? — In-text Questions Page 815
- .2 Standard Units — In-text Questions Page 83 & 845
- .3 Correct Way of Measuring Length — In-text Questions Page 84 & 855
- .3 Correct Way of Measuring Length — Activity 5.1: Let us measure Page 865
- .4 Measuring the Length of a Curved Line — In-text Questions Page 875
- .5 Describing Position — In-text Questions Page 87 & 885
- .5 Describing Position — In-text Questions Page 895
- .6 Moving Things — Activity 5.2: Let us explore Page 905
- .6 Moving Things — Think it over! Page 915
- .7 Types of Motion — Activity 5.3: Let us explore Page 91 & 925
- .7 Types of Motion — Activity 5.4: Let us investigate Page 925
- .7 Types of Motion — Activity 5.5: Let us investigate Page 935
- .7 Types of Motion — Activity 5.6: Let us investigate Page 945
- .7 Types of Motion — Activity 5.7: Let us identify Page 94 & 955
- Chapter exercises — Let us enhance our learning Page 97 & 98
- Extended activities and projects — Learning further Page 99 & 100