This MCQ module is based on: Measurement of Length and Motion
TOPIC 18 OF 46
Measurement of Length and Motion
🎓 Class 6
Science
CBSE
Theory
Ch 5 — Measurement of Length and Motion
⏱ ~8 min
🌐 Language: [gtranslate]
🧠 AI-Powered MCQ Assessment
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Myaischool Lt Science Assessment
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[myaischool_lt_science_assessment grade_level="class_6" science_domain="physics" difficulty="basic"]
Chapter Summary — At a Glance
📏 Why Measure?
Ancient units from body parts (cubit, hand-span, pace) change person-to-person. We need standard units that are fixed for everyone.
🌍 SI Unit of Length
The metre (m). Related units: 1 m = 100 cm = 1000 mm; 1 km = 1000 m.
📐 Measuring Correctly
Start from 0 mark; keep eye straight above (no parallax); use thread for curves; tape for long lengths.
🏃 Motion
An object is in motion if its position changes with time compared to a reference point.
🔄 Four Types of Motion
Linear (straight line), Circular (around a centre), Oscillatory (to-and-fro), Rotational (spinning on axis).
🎢 Combined Motion
Real objects often show more than one type: Earth rotates + revolves; a cycle rolls linearly while wheels rotate.
Key Terms to Remember
Measurement
Standard unit
Metre (SI)
Centimetre
Millimetre
Kilometre
Cubit
Hand-span
Parallax error
Estimation
Motion
Rest
Reference point
Linear motion
Circular motion
Oscillatory motion
Rotational motion
Combined motion
NCERT Exercises — Solved
Try each question yourself before clicking Show Solution. Writing the answer first trains your brain!
Q1. Why do we need standard units of measurement?
Different people have different-sized body parts. A tailor's cubit is not equal to a child's cubit, so a shirt measured by one person may not fit another. Standard units (like the metre) are fixed and the same for everyone, everywhere. They help:
- Shopkeepers, customers, engineers and scientists to communicate lengths clearly.
- Results of experiments to be reproduced anywhere in the world.
- Products (clothes, spare parts, medicines) to fit and work correctly.
Q2. List the SI units of length with their conversions.
| Unit | Symbol | Value in metres |
|---|---|---|
| Millimetre | mm | 1 mm = 0.001 m (1 m = 1000 mm) |
| Centimetre | cm | 1 cm = 0.01 m (1 m = 100 cm) |
| Metre | m | 1 m = 1 m (SI base unit) |
| Kilometre | km | 1 km = 1000 m |
Q3. How do we measure the length of a curved line? Describe the method.
Straight rulers cannot follow curves, so we use the thread (string) method:
- Take a thin, inextensible cotton thread.
- Fix one end of the thread at the starting point of the curve (use tape or pin).
- Carefully lay the thread along the entire curve, pressing it so it follows every bend closely.
- Mark the end-point on the thread with an ink dot.
- Remove the thread and lay it straight on a table.
- Measure the distance from the fixed end to the ink mark using a ruler.
Q4. What is a reference point? Give an example.
A reference point is a fixed point or object agreed upon, from which the position or motion of another object is described. Without it, different people give different answers for the same distance.
Example: To tell a visitor the distance from your home to the school, pick a well-known landmark (say, the village bus-stop) as the reference point. Then everyone measures from the same spot: "The school is 500 m north of the bus-stop."
Example: To tell a visitor the distance from your home to the school, pick a well-known landmark (say, the village bus-stop) as the reference point. Then everyone measures from the same spot: "The school is 500 m north of the bus-stop."
Q5. Classify the type of motion: (a) hand of a clock, (b) child on a swing, (c) pebble falling from a tree, (d) earth around the sun, (e) top spinning.
- (a) Hand of a clock → Circular motion (the tip traces a circle).
- (b) Child on a swing → Oscillatory motion (to and fro).
- (c) Pebble falling from tree → Linear motion (straight line down).
- (d) Earth around the Sun → Circular motion (orbital motion; path is nearly circular).
- (e) Top spinning → Rotational motion (spins on its own axis).
Q6. Give two examples each of: linear, circular and oscillatory motion.
- Linear motion: (i) A train moving on a straight track. (ii) An apple falling straight from a tree.
- Circular motion: (i) Tip of the minute hand of a clock. (ii) Blades of a ceiling fan.
- Oscillatory motion: (i) A pendulum of a wall clock. (ii) A child on a park swing.
Q7. Observe different objects around you. Can you express their lengths in appropriate units?
Pick each object and choose the best-fitting unit. Sample table:
Rule of thumb: very small → mm, everyday → cm, room-size → m, city-scale → km.
| Object | Best Unit | Typical Length |
|---|---|---|
| Pencil | cm | ~15 cm |
| Thickness of a page | mm | ~0.1 mm |
| Classroom length | m | ~8 m |
| School playground | m | ~50 m |
| Distance to nearest town | km | ~5 km |
| Width of little finger | cm or mm | ~1 cm (10 mm) |
Q8. You are given a coin. Estimate how many coins are required to be placed one after another along the lengthwise side of a notebook.
A standard one-rupee coin is about 2.5 cm in diameter. A Class 6 notebook's lengthwise side is about 24-25 cm. So the estimated number of coins = 25 ÷ 2.5 = about 10 coins.
Try it: place coins end-to-end along your own notebook and count. Your result should be close to 9 or 10, depending on the coin and notebook size.
Try it: place coins end-to-end along your own notebook and count. Your result should be close to 9 or 10, depending on the coin and notebook size.
Q9. Observe different objects around you. Is it easier to express the lengths of some objects in cm or m, and of others in mm? Make a list.
Best in mm (very small): Thickness of a coin, thickness of a notebook, size of a mustard seed, pinhead, width of an ant, diameter of pencil lead.
Best in cm (everyday): Length of a pencil, width of an eraser, size of a book, hand-span, height of a water bottle, finger length.
Best in m (room/body-size): Height of a person, length of a bed, width of a door, length of a classroom, height of a wall.
Best in km (far away): Distance between villages, length of a river, route to another city.
Choose the unit where the number stays simple (not too small like 0.0002 or too big like 240000).
Best in cm (everyday): Length of a pencil, width of an eraser, size of a book, hand-span, height of a water bottle, finger length.
Best in m (room/body-size): Height of a person, length of a bed, width of a door, length of a classroom, height of a wall.
Best in km (far away): Distance between villages, length of a river, route to another city.
Choose the unit where the number stays simple (not too small like 0.0002 or too big like 240000).
Q10. A roller coaster track is shown in Fig 5.19. A ball starts at point A and escapes through point F. Identify the types of motion of the ball on the roller coaster and the corresponding portions of the track.
| Portion | Type of Motion | Reason |
|---|---|---|
| A → B | Linear (rectilinear) | The track is a straight slope, so the ball moves in a straight line. |
| B → C → D | Circular | This portion is a full vertical loop — the ball travels around a fixed centre. |
| D → E | Oscillatory (wavy) | Wave-like bumps make the ball move up and down repeatedly. |
| E → F | Linear | Final straight slope — the ball rolls down in a straight line. |
Q11. Why is a jet plane faster than a moving car? Estimate their typical speeds.
A jet plane flies high in the sky where the air is thin, so there is very little air resistance slowing it down. Its powerful jet engines push it at very high speeds. A car drives on roads where friction from the road and air slow it down, and its engine is much less powerful.
Typical speeds:
Typical speeds:
- A passenger jet plane: ~800-900 km/h
- A car on the highway: ~60-100 km/h
- A city bus: ~30-50 km/h
- A running person: ~8-15 km/h
Q12. A student measures the length of a table using (i) hand-spans and (ii) a metre-rule. Which is more reliable? Why?
The metre-rule is far more reliable. Reasons:
- The metre-rule uses standard fixed units (cm and mm). Its markings are the same everywhere.
- Hand-span length varies from person to person — a tall student's span is bigger than a smaller student's span. So the same table gives different readings.
- The metre-rule gives more precise values (down to 1 mm), while hand-span can only be counted in whole spans.
- Results from a metre-rule can be repeated by anyone, anywhere, and everyone will agree.
🎉 Chapter 5 Complete!
You now understand why we measure, how to use SI units, and the four types of motion.
Frequently Asked Questions — Measurement of Length and Motion — Chapter 5 Exercises
What does the topic 'Measurement of Length and Motion — Chapter 5 Exercises' cover in Class 6 Science?
The topic 'Measurement of Length and Motion — Chapter 5 Exercises' is part of NCERT Class 6 Science Chapter 5 — Measurement of Length and Motion. It covers the key ideas of measurement, length, motion, SI units, NCERT exercises, MCQ, explained through everyday examples, labelled diagrams and hands-on activities from the NCERT Curiosity textbook. Class 6 students learn simple definitions, see why each idea matters in daily life, and try short experiments and observations. The lesson uses easy language, colourful pictures and small questions so that young learners build a strong base for higher classes and for competency-based questions in CBSE school tests.
Why is 'Measurement of Length and Motion — Chapter 5 Exercises' important for Class 6 NCERT Science?
'Measurement of Length and Motion — Chapter 5 Exercises' is important because it builds the first ideas of science that Class 6 students will use again in Class 7, 8 and beyond. NCERT Chapter 5 — Measurement of Length and Motion — introduces measurement and connects it to things children already see at home, at school and in nature. Learning this topic helps students ask better questions, understand simple news about science, and score well in CBSE tests that use competency-based questions. The chapter also supports NEP 2020 by encouraging curiosity, observation and learning by doing rather than only reading and memorising.
What are the key ideas students should remember from Measurement of Length and Motion — Chapter 5 Exercises?
The key ideas in 'Measurement of Length and Motion — Chapter 5 Exercises' for Class 6 Science are: measurement, length, motion, SI units, NCERT exercises, MCQ. Students should be able to say each term in their own words, give one or two easy examples from daily life, and draw a small labelled diagram where needed. A good way to revise is to make flashcards, write a short note in the science notebook, and solve the NCERT in-text and exercise questions of Chapter 5. Linking every idea to something seen at home or school — in the kitchen, garden, playground or sky — makes these ideas easy to remember for unit tests and the annual CBSE examination.
How is Measurement of Length and Motion — Chapter 5 Exercises taught using activities in NCERT Curiosity Class 6?
NCERT Curiosity Class 6 Science teaches 'Measurement of Length and Motion — Chapter 5 Exercises' through an inquiry-based approach using Predict–Observe–Explain activities. Students first make a guess, then try a small experiment with safe, easily available materials, and finally explain what happened and why. This matches the NEP 2020 focus on learning by doing. For Chapter 5 — Measurement of Length and Motion — the textbook has hands-on tasks, labelled pictures and thinking questions built for Bloom's Taxonomy Levels 1 to 6. Teachers use these activities, along with competency-based questions (CBQs) and assertion–reason items, to check real understanding instead of only rote learning.
How should Class 6 students prepare for the Chapter 5 exercises?
To prepare for the Chapter 5 — Measurement of Length and Motion — exercises in NCERT Class 6 Science, students should first revise the theory in Parts 1–3 and make a short note of definitions and diagrams for measurement, length, motion, SI units, NCERT exercises, MCQ. Next, try each exercise question on their own before looking at the solution. Pay special attention to MCQs, match-the-following, fill-in-the-blanks, assertion–reason and short-answer items, as these often appear in CBSE competency-based tests. Practising with the NCERT Curiosity textbook, the exemplar questions, and the MyAiSchool practice bank helps Class 6 students score better in unit tests and the annual examination.
How does 'Measurement of Length and Motion — Chapter 5 Exercises' connect to other chapters of Class 6 Science?
'Measurement of Length and Motion — Chapter 5 Exercises' connects to many other chapters in NCERT Class 6 Science Curiosity. The ideas of measurement come back when students study related topics like diversity in the living world, food, magnets, measurement, materials, temperature, water, separation, habitats, natural resources and the solar system. For example, what students learn here helps them build mental pictures for later chapters and for Class 7 and Class 8 Science. Teachers often ask cross-chapter questions in CBSE exams to check if students can use what they learned in Chapter 5 — Measurement of Length and Motion — in new situations. This linked approach matches the NEP 2020 and NCF 2023 focus on holistic, competency-based learning.
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