NCERT Solutions for Class 6 Science Chapter 05 Measurement of Length and Motion

 

Question 1. Some lengths are given in Column I of Table. Some units are given in Column II. Match the lengths with the units suitable for measuring those lengths.
Answer:

In simple words: Pick the right unit for each thing you need to measure. Use kilometres for very far distances, metres for big things like a playground, centimetres for small things like an eraser, and millimetres for tiny things like a coin's thickness.

Exam Tip: Remember that bigger distances use bigger units (km), while tiny things use tiny units (mm). Match each object to the unit that makes sense for its size.

 

Question 2. Read the following statements and mark True (T) or False (F) against each.
(i) The motion of a car moving on a straight road is an example of linear motion.
(ii) Any object which is changing its position with respect to a reference point with time is said to be in motion.
(iii) 1 km = 100 cm
Answer:
(i) The motion of a car moving on a straight road is an example of linear motion. [T]
(ii) Any object which is changing its position with respect to a reference point with time is said to be in motion. [T]
(iii) 1 km = 100 cm [F]
In simple words: A car on a straight road moves in a straight line, which is linear motion - True. Something moves when it changes where it is - True. But 1 km equals 1000 metres, which equals 100,000 centimetres, not 100 - False.

Exam Tip: Always recall that 1 km = 1000 m = 100,000 cm. For motion questions, check if the path is straight (linear), curved (circular), or back-and-forth (oscillatory).

 

Question 3. Which of the following is not a standard unit of measuring length?
(i) millimetre
(ii) centimetre
(iii) kilometre
(iv) handspan
Answer: (iv) handspan
In simple words: Millimetre, centimetre, and kilometre are standard units used everywhere. A handspan is not standard because it changes from person to person.

Exam Tip: Standard units do not change from person to person. Non-standard units like handspan, footspan, and arm length vary, so they are not reliable for measuring.

 

Question 4. Search for the different scales or measuring tapes at your home and school. Find out the smallest value that can be measured using each of these scales. Record your observations in a tabular form.
Answer: Observations of Different Scales or Measuring Tapes:

In simple words: Look at measuring tools in your home and school. Write down the smallest size each one can show. Most rulers and tapes can measure down to 1 millimetre.

Exam Tip: The smallest division on a measuring scale shows the smallest value you can measure. Always check what the smallest marking is on each tool before using it.

 

Question 5. Suppose the distance between your school and home is 1.5 km. Express it in metres.
Answer: The distance between school and home is 1.5 km.
Expressed in metres: 1.5 km = 1.5 × 1000 = 1500 metres.
In simple words: To change kilometres to metres, multiply by 1000. So 1.5 km becomes 1500 metres.

Exam Tip: Always remember the conversion: 1 km = 1000 m. Multiply the number of kilometres by 1000 to get metres.

 

Question 6. Take a tumbler or a bottle. Measure the length of the curved part of the base of glass or bottle and record it.
Answer: Measuring Curved Part of Tumbler/Bottle:
Take a flexible measuring tape and wrap it around the curved part of the tumbler or bottle's base. Record the measurement in centimetres or millimetres based on what your tape shows.
In simple words: Wrap a soft measuring tape around the curved bottom of a glass or bottle. Write down how long it is in centimetres or millimetres.

Exam Tip: Use a flexible measuring tape, not a rigid ruler, because curved surfaces cannot be measured with straight tools. Keep the tape snug but not too tight around the curve.

 

Question 7. Measure the height of your friend and express it in (i) metres (ii) centimetres and (iii) millimetres.
Answer: Height measurement of my friend:
In metres (m): 1.6 m
In centimetres (cm): 160 cm
In millimetres (mm): 1600 mm
In simple words: When you measure a person's height, you can write it in different units. 1.6 metres is the same as 160 centimetres and the same as 1600 millimetres - just different ways to say the same length.

Exam Tip: All three measurements show the same height in different units. Remember: 1 m = 100 cm = 1000 mm. Converting between units means multiplying or dividing by these numbers.

 

Question 8. You are given a coin. Estimate how many coins are required to be placed one after the other lengthwise, without leaving any gap between them, to cover the whole length of the chosen side of a notebook. Verify your estimate by measuring the same side of the notebook and the size of the coin using a 15-cm scale.
Answer: The length of the side of your notebook is 30 cm. The size of the coin is 2.5 cm. Therefore, the coin to estimate the number of coins needed: (30 cm)/(2.5 cm) = 12 coins
In simple words: Measure the notebook's edge and the coin's width. Divide the notebook length by the coin width to find how many coins fit end to end without gaps.

Exam Tip: Always verify your estimate by actually measuring both the notebook and the coin. This practical check teaches you that estimation and measurement work together.

 

Question 9. Give two examples each for linear, circular and oscillatory motion.
Answer:
Examples of Different Types of Motion
Linear Motion: Car moving on a straight road, a person walking straight ahead.
Circular Motion: Ferris wheel, the motion of a ceiling fan.
Oscillatory Motion: Pendulum of a clock, the motion of a swing.
In simple words: Linear motion is moving in a straight line. Circular motion is moving in circles or loops. Oscillatory motion is moving back and forth, like a swing.

Exam Tip: When identifying types of motion, look at the path: Is it straight (linear), circular, or back-and-forth (oscillatory)? Give real-life examples from your surroundings.

 

Question 10. Observe different objects around you. It is easier to express the lengths of some objects in mm, some in cm and some in m. Make a list of three objects in each category and enter them in the Table 5.6.
Answer:

Explanation
Millimetres (mm): These are very small measurements, ideal for thin objects like the thickness of a coin, the width of a pencil, and the thickness of a book cover.
Centimetres (cm): These are medium measurements, suitable for objects like the length of a pen, the width of a notebook, and the height of a coffee mug.
Metres (m): These are large measurements, perfect for tall or long objects like the height of a door, the length of a table, and the height of a person.
In simple words: Use millimetres for tiny things, centimetres for medium things, and metres for big things. Pick the unit that makes the number easy to work with.

Exam Tip: Choose the unit that gives a number that is easy to understand and use. Avoid very small numbers (like 0.005 m) or very large numbers (like 5000 mm) - pick the unit in between.

 

Question 11. A rollercoaster track is made in the shape shown in Figure. A ball starts from point A and escapes through point F. Identify the types of motion of the ball on the rollercoaster and corresponding portions of the track.
Answer: To identify the types of motion of the ball on the rollercoaster and the corresponding portions of the track in the image:
Linear Motion
Portions: A to B and E to F: The ball moves in a straight line along these sections.
Curved Motion
Portions: B to C: The ball moves along a curved path between these points.
Circular Motion
Portion: C to E: The ball moves in a circular loop from C to E.
Conclusion:
A to B: Linear motion
B to C: Curved motion
C to E: Circular motion
E to F: Linear motion
In simple words: Look at each part of the track. Where it is straight, the ball moves straight. Where it curves, the ball follows the curve. Where it loops, the ball goes around in a circle.

Exam Tip: Always identify the shape of the path first. Straight paths mean linear motion, curved paths mean curved motion, and circular loops mean circular motion.

 

Question 12. Tasneem wants to make a metre scale by herself. She considers the following materials for it - plywood, paper, cloth, stretchable rubber and steel. Which of these should she not use and why?
Answer: Tasneem should not use stretchable rubber to make a metre scale.
Reason: Stretchable rubber is not suitable for making a measuring scale because it can stretch and deform easily, leading to inaccurate measurements. A metre scale needs to be rigid and non-stretchable to ensure that the measurements are consistent and reliable.
Better Options
Plywood: Rigid and durable.
Steel: Rigid, durable, and provides accurate measurements.
Paper: Can be used if properly reinforced to prevent bending.
Cloth: Flexible and can be used for measuring curved surfaces but not ideal for precise measurements like a metre scale.
Stretchable rubber should be avoided as it can change its length when stretched, which would not give consistent measurements.
In simple words: Do not use stretchable rubber because it can get longer or shorter. A measuring scale must stay the same size all the time, so you need hard, stiff materials like steel or plywood.

Exam Tip: For a measuring scale, choose materials that are rigid, durable, and do not change shape or length. Steel and plywood are the best choices; rubber and cloth are unsuitable.

 

Question 13. Think, design and develop a card game on conversion of units of length to play with your friends.
Answer:
Card Game: Length Master
Objective: Convert units of length correctly to win cards.
Setup
Length Cards: Each card has a length with a unit (e.g., 2 m, 150 cm).
Conversion Cards: Each card asks for a specific conversion (e.g., Convert to cm).
Reference Cards: Show conversion formulas (e.g., 1 m = 100 cm).
Rules
Draw one Length Card and one Conversion Card.
Convert the length as asked (e.g., 2 m to 200 cm).
Check with Reference Cards.
Keep the card if correct. If not, put it back.
The player with the most cards wins.
In simple words: Make cards with lengths on them. Make other cards that ask you to change from one unit to another. Players take turns, do the conversion, and check if they are right. Whoever gets the most correct answers wins.

Exam Tip: This game helps you remember conversion factors: 1 m = 100 cm = 1000 mm, 1 km = 1000 m. Playing games makes learning units fun and easier to remember.