How to Use This Page
This page contains complete solutions for the TN Class 6 Science chapter on Measurements. Use it as follows:
- MCQ, True/False, Fill in the Blanks — quick self-check before exams
- Key Concepts table — fast revision of definitions and formulas
- Match the Following — test your instrument and unit knowledge
- Answer Briefly (2-mark) — detailed 3–5 sentence answers for short-answer questions
- Answer in Detail (5-mark) — fully worked-out long answers with structured sub-points
- Common Mistakes & Exam Checklist — avoid losing marks on silly errors
Key Concepts (Quick Recap)
| Term | Definition |
|---|---|
| Measurement | Comparison of an unknown quantity with a known standard quantity |
| Physical Quantity | A quantity that can be measured (e.g., length, mass, time) |
| SI Units | International System of Units — a uniform set of units used worldwide |
| Length | The distance between two points; SI unit is metre (m) |
| Mass | The amount of matter in an object; SI unit is kilogram (kg) |
| Time | The interval between two events; SI unit is second (s) |
| Volume | The space occupied by a substance; SI unit is cubic metre (m³) |
| Temperature | The degree of hotness or coldness; SI unit is kelvin (K) |
| Fundamental Quantity | A quantity measured directly and independent of other quantities (length, mass, time) |
| Derived Quantity | A quantity obtained from fundamental quantities (e.g., area, volume, speed) |
| Parallax Error | Error caused by viewing a measurement scale from an angle instead of directly above |
| Unit Conversion | 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm, 1 kg = 1000 g |
| Beam Balance | An instrument used to measure mass by comparing with known standard masses |
| Odometer | A device that measures the distance travelled by an automobile |
I. Choose the Correct Answer (MCQ)
Q1. The girth of a tree can be measured by (a) metre scale (b) metre rod (c) plastic ruler (d) measuring tape ✓
Q2. The conversion of 7 m into cm gives (a) 70 cm (b) 7 cm (c) 700 cm ✓ (d) 7000 cm
Q3. Quantity that can be measured is called (a) Physical quantity ✓ (b) Measurement (c) unit (d) motion
Q4. Choose the correct one (a) km > mm > cm > m (b) km > mm > m > cm (c) km > m > cm > mm ✓ (d) km > cm > m > mm
Q5. While measuring length using a ruler, the position of your eye should be (a) Left side of the point (b) Vertically above the point ✓ (c) Right side of the point (d) Anywhere
Additional MCQs:
Q6. In which SI unit can you measure your height? (a) Kilogram (b) Litre (c) Metre ✓ (d) Second
Q7. Unit of electric current in the SI system? (a) Kelvin (b) Ampere ✓ (c) seconds (d) Volt
Q8. ______ is used to measure accurate time of the activity. (a) Clock (b) Watch (c) Stop clock ✓ (d) Sundial
Q9. Instruments used in measuring volume of liquid: (a) cylinder (b) pipettes (c) burettes (d) All ✓
Q10. SI unit for Volume: (a) m² (b) m (c) m³ ✓ (d) none
Q11. Twenty decimetre equals: (a) 2 km (b) 20 cm (c) 2 metre ✓ (d) 200 mm
Q12. ______ is used to measure mass. (a) Stop clock (b) Beam balance ✓ (c) Sundial (d) Graduated cylinder
Q13. The metric system was created by the ______ in 1790. (a) Greek (b) Australians (c) Russians (d) French ✓
Q14. The moon's gravitational pull is one ______ of the earth's pull. (a) seventh (b) sixth ✓ (c) fifth (d) fourth
II. True or False
Additional True/False:
III. Fill in the Blanks
1. SI Unit of length is symbolically represented as → m 2. 500 gm = 0.5 kilogram 3. Distance between Delhi and Chennai can be measured in → Kilometre 4. 1 m = 100 cm 5. 5 km = 5000 m
Additional Fill in the Blanks:
6. _____ are push or pull by an animate or inanimate agency. → Forces 7. Application of force results in motion from a state of _____ → rest 8. Potatoes : Kilogram; Water? → Litre 9. Stop clock : accurate time; ______ : accurate weight → Electronic balance 10. Mass : Balance; Length? → Measuring tape 11. Amount of matter : mass; Gravitational Pull? → Weight
IV. Analogy
Q1. Sugar : Beam balance; Lime juice? → Measuring Jar Q2. Height of a person : cm; length of your sharpened pencil lead? → mm Q3. Milk : volume; vegetables? → mass
Match the Following
| Column A | Column B |
|---|---|
| Beam balance | Mass |
| Measuring tape | Length / Girth |
| Graduated cylinder | Volume of liquid |
| Stop clock | Time |
| Odometer | Distance travelled |
| Electronic balance | Accurate mass |
| Speedometer | Speed |
| Thermometer | Temperature |
V. Answer Briefly (2-mark)
Q1. Define measurement. Measurement is the process of comparing an unknown physical quantity with a known standard quantity called a unit. For example, when we say a pencil is 15 cm long, we are comparing the pencil's length with the standard unit of centimetre. Every measurement consists of two parts: a number and a unit. Without a unit, a number alone does not convey any meaningful information about the quantity measured.
Q2. Define mass. Mass is the measure of the amount of matter present in an object. It is a fundamental physical quantity and its SI unit is the kilogram (kg). Mass remains the same wherever the object is — on Earth, on the Moon, or in space. It is measured using instruments such as a beam balance or an electronic balance.
Q3. What is the International System of Units (SI units)? The International System of Units, known as SI units, is a globally accepted set of standard units used for expressing measurements. It was developed to ensure uniformity so that scientists and people worldwide use the same units. Examples include metre for length, kilogram for mass, and second for time. SI units eliminate confusion caused by different local or traditional units of measurement.
Q4. What is parallax error? Parallax error occurs when a measurement is read from an angle rather than from a position directly above the scale marking. If your eye is to the left or right of the point being measured, the reading appears different from the true value. To avoid parallax error, the eye must be positioned vertically above the point of measurement. This is one of the most common mistakes students make during practical exams.
Q5. What is an odometer? An odometer is a device fitted in automobiles that measures and displays the total distance the vehicle has travelled. It works by counting the number of rotations of the wheel and converting that into distance. It is different from a speedometer, which shows how fast the vehicle is moving at any given moment.
Q6. Convert 43.65 km into metre and cm. Since 1 km = 1000 m, we multiply: 43.65 × 1000 = 43,650 m. To convert to centimetres, since 1 km = 100,000 cm, we multiply: 43.65 × 100,000 = 4,365,000 cm. Always remember to multiply by the correct conversion factor — 1000 for km→m and 100,000 for km→cm.
Q7. What are the rules to make accurate measurement with a scale? Place the scale in contact with the object along its length and ensure the zero mark of the scale aligns with one end of the object. Your eye must be exactly vertically above the point where the measurement is taken to avoid parallax error. If the zero mark is worn out, use any other full mark and subtract the starting reading from the final reading to get the correct length.
Q8. What instruments are used to measure time? How have they evolved? Early instruments for measuring time included the sundial and the sand clock, which relied on natural phenomena. Modern timekeeping uses clocks, watches, and the stop clock for precise measurements. A stop clock is especially useful in laboratories and sports because it can measure time intervals accurately to fractions of a second.
VI. Answer in Detail (5-mark)
Q1. Explain two methods to measure the length of a curved line.
Method 1 — Using a string:
- Take a piece of string or thread and place it along the curved line carefully, ensuring it follows the exact path of the curve.
- Mark the beginning and end points on the string using a sketch pen or by holding the string at those points.
- Stretch the string straight along a metre scale and read the distance between the two markings.
- This length on the string equals the length of the curved line. The string method is simple and works well for gently curved lines.
Method 2 — Using a divider:
- Set the two legs of a divider to a small, known distance (e.g., 0.5 cm or 1 cm) using a ruler.
- Place one leg of the divider at the starting point of the curved line and mark where the other leg falls on the curve.
- Move the divider along the curve, each time placing one leg where the previous one ended, and count the number of such segments.
- If there is a small leftover portion at the end that is shorter than the divider spacing, measure it separately with a scale.
- Total length = (number of segments × length of each segment) + leftover length. This method is more precise for tight curves.
Q2. Distinguish between fundamental quantities and derived quantities with examples.
Physical quantities are classified into two types based on how they are measured:
Fundamental Quantities:
- These are quantities that can be measured directly and do not depend on any other quantity for their definition.
- There are seven fundamental quantities in the SI system: length, mass, time, temperature, electric current, amount of substance, and luminous intensity.
- Their units (metre, kilogram, second, kelvin, ampere, mole, candela) are called fundamental units and are defined independently.
- Example: The length of a table can be measured directly using a measuring tape without needing any other quantity.
Derived Quantities:
- These are quantities that are obtained by combining two or more fundamental quantities using mathematical operations (multiplication or division).
- Examples include area (length × length = m²), volume (length × length × length = m³), speed (length ÷ time = m/s), and density (mass ÷ volume = kg/m³).
- Their units are called derived units because they are formed from fundamental units.
- Example: To find the area of your classroom, you measure length and breadth (both fundamental) and then multiply them to get the derived quantity — area.
VII. Answer in a Word or Two
Q1. Full form of SI system → International System of Units Q2. Name one instrument used for measuring mass → Beam balance Q3. Odd one out: Kilogram, millimetre, centimetre, nanometre → Kilogram (measures mass; rest measure length) Q4. SI Unit of mass → Kilogram Q5. Two parts present in a measurement → A number and the unit
VIII. Find the Answer within the Grid
1. 10⁻³ is one ______ → Millimetre 2. SI Unit of time ______ → Second 3. Cross view of reading for measurement leads to ______ → Error 4. ______ is what a clock reads. → Time 5. ______ is the amount of substance present in an object. → Mass 6. ______ can be taken to get final reading of different students' recordings. → Average 7. ______ is a fundamental quantity. → Length 8. ______ shows the distance covered by an automobile. → Odometer 9. A tailor uses ______ to take measurements to stitch a cloth. → Tape 10. Liquids are measured with this physical quantity. → Litre
IX. Answer in a Sentence or Two
Q1. Define measurement. The comparison of unknown quantities with some known quantities is known as measurement.
Q2. Define mass. Mass is the measure of the amount of matter in an object.
Q3. The distance between two places is 43.65 km. Convert it into metre and cm. 43.65 km = 43,650 m; 43.65 km = 4,365,000 cm
Q4. What are the rules to make accurate measurement with a scale? (1) Avoid parallax error. (2) Your eye must be exactly in front of, vertically above, the point where the measurement is taken.
X. Solve the Following
Q1. Distance between school and house is 2250 m. Express in km. 2250 m = 2.250 km
Q2. Scale reading at one end of a pencil is 2.0 cm and at the other end is 12.1 cm. What is the length? 12.1 cm – 2.0 cm = 10.1 cm (or 10 cm and 1 mm)
XI. Write in Detail
Q1. Explain two methods to measure the length of a curved line.
Method 1 — Using a string: 1. Place a string along the curved line 2. Mark the beginning and end points on the string 3. Stretch the string along a meter scale and measure between the two markings 4. This gives the length of the curved line
Method 2 — Using a divider: 1. Set divider legs 0.5 cm or 1 cm apart using a ruler 2. Place it at one end of the curved line, mark the other end 3. Move it along the line repeatedly, counting segments 4. Measure any leftover part with a scale 5. Total length = (number of segments × length of each segment) + length of leftover part
Additional Short Answers
Q1. What is the international system of units or SI units? For the sake of uniformity all over the world, we have adopted a common set of units to express measurements that are called an international system of units or SI units.
Q2. Give examples of larger length measures. Height of a building, length of a banner, height of a lamp post.
Q3. Units of very small lengths? Millimetre and centimetre.
Q4. What is parallax? Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight.
Q5. Where are electronic balances used? Grocery shops and jewellery shops.
Q6. What is an odometer? It is a device used for indicating distance travelled by an automobile.
Q7. Materials needed to find the length of a banana? Meter scale, string/thread, sketch pen.
Q8. Formula to measure the area of your classroom? Length × Breadth
Q9. Device for accurate weight measurement? Electronic balance.
Q10. Earlier instruments used to measure time? Sand clock and Sundial.
Q11. Who invented the ruler or scale? William Bedwell.
Q12. Alloy used to make the standard metre rod? An alloy of platinum and iridium.
Common Mistakes to Avoid
1. SI unit of length ❌ Writing kilometre or centimetre as the SI unit of length ✅ The SI unit of length is metre (m); km and cm are derived units
2. Eye position while reading a scale ❌ Looking from the side of the scale to take a reading ✅ Position your eye vertically above the point of measurement to avoid parallax error
3. Hand span as a measurement unit ❌ Using hand span or cubit as a reliable measure of length ✅ Hand span varies from person to person; always use standard units
4. Unit conversion — mm to cm ❌ Thinking 10 mm = 1 cm is wrong, or confusing it with 100 mm = 1 cm ✅ 10 mm = 1 cm (divide millimetres by 10 to get centimetres)
5. Unit conversion — m to cm ❌ Converting 7 m as 70 cm or 7000 cm ✅ 7 m = 700 cm (multiply metres by 100 to get centimetres)
6. Speedometer vs. Odometer ❌ Confusing speedometer with odometer ✅ Speedometer measures speed; odometer measures distance travelled
7. Mass vs. Weight ❌ Using mass and weight interchangeably ✅ Mass is the amount of matter (constant everywhere); weight is the gravitational pull on mass (varies with location)
8. Fundamental vs. Derived quantities ❌ Listing area, volume, or speed as fundamental quantities ✅ Only length, mass, time, temperature, electric current, amount of substance, and luminous intensity are fundamental; area and volume are derived
Exam Checklist
- [ ] Can define measurement, mass, and SI units
- [ ] Know SI units for length (m), mass (kg), time (s), volume (m³)
- [ ] Can convert between units (km↔m↔cm↔mm)
- [ ] Know the two methods to measure curved lines (string and divider)
- [ ] Understand parallax error and how to avoid it
- [ ] Know the difference between fundamental and derived quantities
- [ ] Can identify measuring instruments (beam balance, measuring tape, graduated cylinder, stop clock)
- [ ] Know that 1 m = 100 cm, 1 km = 1000 m, 1000 g = 1 kg
- [ ] Can solve numerical problems (distance conversions)
- [ ] Can distinguish between mass and weight with examples
- [ ] Know that the metric system was created by the French in 1790
- [ ] Can name early time-keeping devices (sundial, sand clock) and the modern stop clock