RBSE Solutions Class 6 Science Chapter 5 Measurement of Length and Motion

Measurement of Length and Motion Class 6 Questions and Answers

RBSE Class 6 Science Chapter 5 Measurement of Length and Motion Question Answer

Measurement of Length and Motion Class 6 Question Answer - InText

 

Question 1. Would it be convenient to use the unit metre to measure larger lengths, such as the length of a railway track between two cities, or to measure smaller lengths, such as the thickness of a page of a book?

🎯 Exam Tip: When evaluating units, consider the practical scale of the object being measured; a metre is suitable for medium lengths but not extremely large or small ones.

 

Question 2. What do such kilometre stones indicate?
Answer: A kilometre stone shows how far a certain place is from a starting point, like a big city. These stones help travelers know their distance from important locations.
In simple words: Kilometre stones show the distance from a specific starting place.

🎯 Exam Tip: Explain what a kilometre stone is and its purpose, clearly stating its function in relation to distance and a reference point.

RBSE Class 6th Science Chapter 5 Question Answer - Exercise

 

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: Match each item in Column-I with the most fitting unit from Column-II. Remember that long distances use kilometres, tiny things use millimetres, and everyday objects use centimetres or metres.

🎯 Exam Tip: Always consider the size of the object when choosing the correct unit of measurement to ensure accuracy.

 

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) True
(ii) True
(iii) False (Because \( 1 \) km equals \( 1000 \) metres or \( 100,000 \) centimetres, not \( 100 \) cm).
In simple words: For each sentence, decide if it is correct or incorrect. Linear motion is straight, motion is change in position, and 1 kilometre is much more than 100 centimetres.

🎯 Exam Tip: Clearly understand the definitions of different types of motion and the conversion factors for units of length. A common error is mixing up kilometre and centimetre conversions.

 

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: A handspan changes from person to person, so it is not a fixed or standard way to measure length. Other options like millimetre, centimetre, and kilometre are fixed units.

🎯 Exam Tip: Remember that standard units must be uniform and consistent, meaning they are the same for everyone and everywhere. Non-standard units, like body parts, vary between individuals.

 

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:

Observation Table

In simple words: Different tools measure different smallest amounts. A geometric ruler can measure as small as 1 millimetre, a metre scale typically 1 centimetre, and an inch tape as small as 1 inch.

🎯 Exam Tip: Always note the least count (smallest division) of any measuring instrument before using it, as this determines the precision of your measurement.

 

Question 5. Suppose the distance between your school and home is 1.5 km. Express it in metres.
Answer: We know that \( 1 \) kilometre \( = 1000 \) metres.
So, to convert \( 1.5 \) km to metres, we multiply it by \( 1000 \).
\( 1.5 \) km \( = 1.5 \times 1000 \)
\( = 1500 \) metres
In simple words: To change kilometres into metres, just multiply the number of kilometres by 1000. So, 1.5 km becomes 1500 metres.

🎯 Exam Tip: Remember the basic conversion factor: 1 kilometre is always equal to 1000 metres. This is crucial for unit conversions.

 

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: The curved base of a glass or bottle cannot be measured with a straight ruler. To measure it, you need a flexible tool like a measuring tape or a piece of thread. The length of the curved part of the bottom of the glass is approximately \( 17.2 \) cm.
In simple words: Use a flexible tape or thread to measure the curved bottom of a bottle. A sample measurement could be around 17.2 cm.

🎯 Exam Tip: For curved lengths, always use a flexible measuring tool, such as a string or tailor's tape, and then measure the string's length with a straight scale.

 

Question 7. Measure the height of your friend and express it in (i) metres (ii) centimetres and (iii) millimetres.
Answer: Let's say the height of a friend is \( 1.25 \) metres.
(i) Height in metres \( = 1.25 \) metres
(ii) To convert metres to centimetres, we know \( 1 \) metre \( = 100 \) centimetres.
So, \( 1.25 \) m \( = 1.25 \times 100 = 125 \) cm.
(iii) To convert metres to millimetres, we know \( 1 \) metre \( = 1000 \) millimetres.
So, \( 1.25 \) m \( = 1.25 \times 1000 = 1250 \) mm.
In simple words: If a friend is 1.25 metres tall, that's 125 centimetres or 1250 millimetres. You multiply by 100 for centimetres and by 1000 for millimetres.

🎯 Exam Tip: Be careful with decimal places when converting units; moving the decimal point correctly is essential for accurate results.

 

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: First, estimate how many coins you think will fit along one side of the notebook. Then, measure the actual length of the notebook side with a 15-cm scale. Next, measure the diameter of one coin. Finally, divide the notebook's length by the coin's diameter to find the exact number of coins needed. For example, if you guess 9 coins, and the measurements show it takes 10 coins, then your estimate was close. The actual measurement will show the precise number.
In simple words: Guess how many coins fit along a notebook. Then, measure the notebook and one coin. Divide the notebook's length by the coin's width to find the correct number of coins.

🎯 Exam Tip: Emphasize the importance of both estimation and precise measurement for comparing and validating results in practical science experiments.

 

Question 9. Give two examples each for linear, circular and oscillatory motion.
Answer:
Examples of linear motion:
(i) A fruit falling from a tree moves in a straight line downwards.
(ii) Students marching past in a straight line on a parade ground.
Examples of circular motion:
(i) The rotation of a bicycle wheel while riding.
(ii) A merry-go-round when it spins.
Examples of oscillatory motion:
(i) The motion of a clock's pendulum swinging back and forth.
(ii) A child swinging on a swing set.
In simple words: Linear motion is straight, circular motion is in a circle, and oscillatory motion is swinging back and forth. Falling fruit and marching are linear. A bicycle wheel and merry-go-round are circular. A clock pendulum and a child on a swing are oscillatory.

🎯 Exam Tip: Clearly define each type of motion and provide distinct, everyday examples for each to show full understanding.

 

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:

Table 5.6: Sizes of objects around us

In simple words: We use millimetres (mm) for very small things like glass thickness, centimetres (cm) for medium things like a table's length, and metres (m) for large things like a house.

🎯 Exam Tip: When listing objects, make sure they are clearly distinguishable by their typical size to fit the specified units (mm, cm, m).

 

Question 11. A rollercoaster track is made in the shape shown in Fig. 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:

1. Linear motion-

(i) From point 'A' to point 'B' (This is a straight segment).
(ii) From point 'E' to F (This is also a straight segment).

2. Circular motion-

(i) Between the points 'B' 'C' 'D' 'E' (This section forms a curved or loop-like path).

A rollercoaster involves many types of motion, depending on the shape of its path.

In simple words: On the rollercoaster, the ball moves in a straight line (linear motion) from A to B and E to F. It moves in a circle or curve (circular motion) from B to C, C to D, and D to E.

🎯 Exam Tip: When analyzing motion, look for straight paths for linear motion and curved or circular paths for circular motion. Identify each segment clearly.

 

Question 12. Tasneem wants to make a metre scale by herself. She considers the following materials for it -plywood,

🎯 Exam Tip: When creating measuring tools, it's important to choose materials that are rigid and not easily affected by changes in temperature or humidity, to maintain accuracy.

 

Question 13. Think, design and develop a card game on conversion of units of length to play with your friends.
Answer: You can create different cards, each showing a length in a specific unit like millimetres (mm), centimetres (cm), or kilometres (km). Then, other cards would have the equivalent value in a different unit. Players match these cards, for example, a card with "1 kilometre" would be matched with a card showing "1000 metres." This helps in practicing unit conversions.
In simple words: Make cards with different lengths (like 1 km) and other cards with their equal values in other units (like 1000 m). Players then match the cards.

🎯 Exam Tip: A well-designed game for unit conversion should clearly display the original unit and its equivalent in another unit, reinforcing the conversion factors.

RBSE Class 6 Science Chapter 5 Important Questions

Multiple Choice Questions

 

Question 1. The suitable unit for long distance measurement is-
(a) metre
(b) centimetre
(c) kilometre
(d) millimetre
Answer: (c) kilometre
In simple words: Kilometre is the best unit for measuring very long distances, like between cities.

🎯 Exam Tip: Select the unit that is most appropriate for the scale of the measurement; kilometres are ideal for large distances due to their magnitude.

 

Question 2. What type of motion does a rolling ball show?
(a) Linear motion
(b) Circular motion
(c) Vertical and linear motion
(d) Linear and circular motion
Answer: (d) Linear and circular motion
In simple words: A rolling ball moves forward in a straight line (linear motion) while also spinning around its own axis (circular motion). It's doing both at once.

🎯 Exam Tip: Understand that objects can exhibit multiple types of motion simultaneously; a rolling object combines translational (linear) and rotational (circular) movement.

 

Question 3. Motion along a straight line is called-
(a) Circular motion
(b) Oscillatory motion
(c) Linear motion
(d) All of the options
Answer: (c) Linear motion
In simple words: When something moves in a perfectly straight path, we call that linear motion.

🎯 Exam Tip: Clearly distinguish between different types of motion based on the path taken by the moving object; linear motion implies a straight path.

 

Question 5. What was used to measure small lengths in ancient times?
(a) Feet
(b) Hands
(c) Fist
(d) Fingers (cingula)
Answer: (d) Fingers (cingula)
In simple words: Long ago, people used parts of their body, like their fingers (called cingula), to measure small lengths.

🎯 Exam Tip: Note the difference between modern standard units and ancient non-standard units, which often involved body parts and varied from person to person.

 

Question 6. The value of 1 inch is-
(a) 1.54 cm
(b) 2.54 cm
(c) 2.45 cm
(d) 2.46 cm
Answer: (b) 2.54 cm
In simple words: One inch is equal to 2.54 centimetres. This is a standard conversion value used in many countries.

🎯 Exam Tip: Memorize common conversion factors like 1 inch = 2.54 cm, as they are frequently tested and useful in practical applications.

 

Question 7. The symbol of millimetre is-
(a) mM
(b) cm
(c) mm
(d) m
Answer: (c) mm
In simple words: The short way to write millimetre is "mm". This is its official symbol in the metric system.

🎯 Exam Tip: Pay close attention to the correct symbols for units of measurement; "mm" is specific to millimetre, avoiding confusion with other units.

 

Question 8. The motion of the swing is-
(a) Linear motion
(b) Oscillatory motion
(c) Circular motion
Answer: (b) Oscillatory motion
In simple words: A swing moves back and forth around a fixed point, which is called oscillatory motion.

🎯 Exam Tip: Recognize oscillatory motion as repetitive movement back and forth about a central point, like a swing or a pendulum.

 

Question 10. An example of oscillatory motion is-
(a) Soldiers parade
(b) Rolling of ball
(c) Pendulum
(d) All of the options
Answer: (c) Pendulum
In simple words: A pendulum swings back and forth in a regular way, showing oscillatory motion. Soldiers marching is linear, and a rolling ball is linear and circular.

🎯 Exam Tip: Clearly differentiate between linear, circular, and oscillatory motions by associating specific examples with their correct motion type.

Fill in the blanks

 

Question 1. The change in position with respect to time is called .................................
Answer: motion
In simple words: When an object's place changes over time, it is called motion.

🎯 Exam Tip: Define motion precisely as a change in position relative to a reference point over time.

 

Question 2. The motion of the second hand of a clock is an example of ................................. motion.
Answer: circular
In simple words: The second hand of a clock moves in a circle, so it's circular motion.

🎯 Exam Tip: Understand that any object moving in a circular path, even if repeating, is fundamentally exhibiting circular motion.

 

Question 3. While writing the length, always leave a space between the ................................. and the .................................
Answer: number, unit
In simple words: Always put a space between the number and its unit, like "5 cm" not "5cm".

🎯 Exam Tip: Correct spacing between the numerical value and its unit is a small but important detail in scientific writing for clarity and convention.

 

Question 4. Both circular motion and oscillatory motion are ................................. in nature.
Answer: periodic
In simple words: Both circular motion (like a clock hand) and oscillatory motion (like a swing) repeat after a certain time, making them periodic.

🎯 Exam Tip: The key characteristic of periodic motion is its repetition after a fixed interval of time, which applies to many circular and oscillatory movements.

True/False

 

Question 1. Motion along a straight line is called circular motion. (True/False)
Answer: False
In simple words: Movement in a straight line is linear motion, not circular motion. Circular motion happens in a circle.

🎯 Exam Tip: Avoid confusing linear (straight path) and circular (round path) motion; they are distinct types of movement.

 

Question 2. There are 100 millimetres in one centimetre. (True/False)
Answer: False
In simple words: There are 10 millimetres in one centimetre, not 100.

🎯 Exam Tip: Accurately recall metric conversions; 1 cm = 10 mm, 1 m = 100 cm, and 1 km = 1000 m.

 

Question 3. The symbol for the unit of length metre in m. (True/False)
Answer: True
In simple words: The letter 'm' is the correct and standard symbol for the unit 'metre'.

🎯 Exam Tip: Know the standard symbols for units; 'm' is correctly used for metre, and 'g' for gram, etc.

 

Question 4. The length of a curved line can be measured directly using a metre scale. (True/False)
Answer: False
In simple words: You cannot measure a curved line directly with a straight metre scale. You need a flexible tool like a thread or measuring tape first.

🎯 Exam Tip: Understand the limitations of different measuring instruments; a straight scale is only for straight lines, while flexible tools are needed for curves.

Match the words given in Column-I with Column-II

 

Question 1.

Answer:In simple words: Match the clock hands with circular motion, march past with linear motion, a swing with oscillatory motion, and a pendulum with periodic motion.

🎯 Exam Tip: Carefully analyze the motion described for each item and pair it with the correct type of motion. Clock hands move in a circle, marching is straight, a swing goes back and forth (oscillatory), and a pendulum repeats its swing regularly (periodic).

 

Question 2.

Answer:In simple words: Match the given millimetre values to their correct conversions in metres, inches, or kilometres. Remember that \( 1000 \) mm equals \( 1 \) metre, \( 1500 \) mm equals \( 1.5 \) metres, \( 50.8 \) mm equals \( 2 \) inches, and \( 2000 \) mm equals \( 0.002 \) kilometres.

🎯 Exam Tip: Be proficient in converting between millimetres, metres, inches, and kilometres, knowing that \( 1 \) inch is approximately \( 25.4 \) mm and \( 1 \) km is \( 1,000,000 \) mm.

Very Short Answer Type Questions

 

Question 1. What is meant by handspan?
Answer: A handspan is the distance measured from the tip of the thumb to the tip of the little finger when the hand is stretched out as wide as possible. It is a non-standard unit of length.
In simple words: Handspan is the length from your thumb to your pinky finger when your hand is open wide.

🎯 Exam Tip: Clearly define handspan as a measurement using the hand and highlight that it's a non-standard unit because it varies from person to person.

 

Question 2. What type of scale is suitable for measuring the thickness of a tree trunk?
Answer: To measure the thickness of a tree trunk, which is a curved surface, a flexible measuring tape is the most suitable tool. A rigid metre scale cannot be wrapped around the trunk.
In simple words: A flexible measuring tape, like a tailor's tape, is best for measuring a tree trunk because it can bend around the curve.

🎯 Exam Tip: Choose measuring tools based on the object's shape; flexible tapes are essential for curved surfaces, while rigid scales are for straight lines.

 

Question 3. What is the correct way of holding a scale?
Answer: To measure correctly, a scale should be held directly in contact with the object along its entire length. This ensures there are no gaps or angles that could lead to incorrect readings.
In simple words: Hold the scale touching the object for the whole length you want to measure.

🎯 Exam Tip: Always place the measuring scale in direct and continuous contact with the object to avoid parallax errors and obtain accurate measurements.

 

Question 4. How do visually impaired students measure length?
Answer: Visually impaired students can measure length using scales that have raised markings. They can feel these markings with their fingers, allowing them to read the measurements by touch.
In simple words: Visually impaired students use scales with raised bumps they can feel to measure lengths.

🎯 Exam Tip: Highlight inclusive methods of measurement, such as tactile scales, which enable visually impaired individuals to perform measurements effectively.

 

Question 5. How many and which are the parts of the result obtained from the measurement of length?
Answer: The result of a length measurement always has two main parts. One part is the numerical value (the number), and the other part is the unit of measurement (like cm or m). For example, in "10 cm," "10" is the number and "cm" is the unit.
In simple words: Every length measurement has two parts: a number (like 5) and a unit (like metres).

🎯 Exam Tip: Emphasize that a complete measurement always includes both a numerical value and a unit, as a number alone is meaningless in measurement.

 

Question 6. How can the length be measured in the case of a curved line?
Answer: To measure a curved line, you can use a thread or a flexible measuring tape. Place the thread exactly along the curve, then straighten the thread and measure its length with a straight ruler. This method accurately captures the entire length of the curve. You cannot use a rigid scale directly for this.
In simple words: To measure a curved line, put a string or flexible tape along it. Then, straighten the string or tape and measure its length with a regular ruler.

🎯 Exam Tip: For curved lines, always use a flexible material like a thread or a measuring tape, which can conform to the shape, and then measure that material's straightened length.

 

Question 8. What is called motion'?
Answer: Motion is defined as the change in an object's position over time, when compared to a fixed reference point. If an object stays in the same place relative to that point, it is considered at rest.
In simple words: Motion means an object is changing its place over time, compared to something that stays still.

🎯 Exam Tip: A complete definition of motion must include the elements of change in position, time, and a reference point, as motion is relative.

 

Question 9. What is 'linear motion'?
Answer: Linear motion occurs when an object moves exactly along a straight line. This type of motion involves movement in a single direction without any curves or turns.
In simple words: Linear motion is when an object moves in a straight path.

🎯 Exam Tip: Focus on the "straight line" aspect when defining linear motion; examples like a car on a straight road reinforce this concept.

 

Question 10. What is 'circular motion'?
Answer: Circular motion happens when an object moves along a path that forms a perfect circle. The object constantly changes direction, but its distance from a central point remains the same.
In simple words: Circular motion is when an object moves around in a circle.

🎯 Exam Tip: Emphasize that in circular motion, the object moves along a curved path that forms a circle, with a constant radius from a central point.

 

Question 11. What is 'periodic motion'?
Answer: Periodic motion is a type of motion where an object repeats its path or movement after a fixed amount of time. The movement cycles over and over again.
In simple words: Periodic motion is when an object does the same movement again and again after a fixed time.

🎯 Exam Tip: The key characteristic of periodic motion is its predictable repetition over a consistent time interval, essential for movements like pendulums or orbiting planets.

 

Question 12. What is measurement?
Answer: Measurement is the process of comparing an unknown quantity to a known, standard quantity of the same type. For example, comparing the length of a table to a standard metre stick.
In simple words: Measurement is comparing something unknown (like a table's length) to something known (like a metre stick).

🎯 Exam Tip: Define measurement as a comparison process between an unknown quantity and a standard unit of the same kind.

 

Question 13. What is meant by unit?
Answer: A unit is a fixed and internationally agreed-upon quantity that is used as a standard for measurement. For example, the metre is a unit for length, and the kilogram is a unit for mass.
In simple words: A unit is a fixed amount (like a metre) that we use to measure things.

🎯 Exam Tip: Explain that units are standardized quantities that allow for consistent and universal measurement, making scientific communication clear.

 

Question 15. What is a 'Jones Counter?
Answer: A 'Jones Counter' is a device typically attached to the wheel of a bicycle or similar vehicle. It's used to measure distances by counting the rotations of the wheel, which helps in calculating how far the bicycle has traveled.
In simple words: A Jones Counter is a tool fixed to a bicycle wheel that helps measure how far it has traveled by counting wheel spins.

🎯 Exam Tip: Describe the Jones Counter as a device that measures distance by counting wheel revolutions, often used in surveying or road measurements.

Short Answer Type Questions

 

Question 1. Why was there a need to develop a uniform measurement system?
Answer: In olden times, people used their body parts like handspans, feet, or fists to measure things. The problem was that these lengths differed from person to person, making measurements inconsistent and unreliable. This led to a strong need for a uniform system, where everyone would get the same measurement for the same length, no matter who was measuring. The metric system was created to solve this problem, providing universal and consistent units for everyone.
In simple words: People used body parts to measure things, but everyone's body is different, causing confusion. So, a common, fair way to measure was needed so everyone got the same answer.

🎯 Exam Tip: Emphasize that the primary reason for a uniform system was to overcome inconsistencies and ensure reliable, comparable measurements across different individuals and regions.

 

Question 2. When can an object be called in motion or at rest? Explain.
Answer: An object is said to be in motion if its position changes continuously with respect to a fixed reference point over time. For example, a car moving past a stationary tree is in motion. Conversely, an object is said to be at rest if its position does not change with respect to a reference point over time. A book lying on a table in a quiet room is at rest relative to the table. Motion and rest are relative concepts, meaning they depend on the chosen reference point.
In simple words: An object is in motion if its place changes over time compared to a still point. It is at rest if its place does not change compared to that point.

🎯 Exam Tip: Clearly define both motion and rest, highlighting that both terms depend on a chosen "reference point" and "time" to be accurately described.

 

Question 3. Both circular motion and oscillatory motion are periodic motion in nature. Explain this statement.
Answer: Periodic motion is any motion that repeats itself after a fixed interval of time. Both circular and oscillatory motions fit this description. In circular motion, like a car going around a round track, the object continuously travels the same circular path over and over again, completing a full circle in a consistent time. Similarly, in oscillatory motion, such as a child on a swing, the object moves back and forth repeatedly over the same path, completing each full swing in a fixed duration. Therefore, both are examples of motion that cycle through the same pattern regularly.
In simple words: Both circular motion (like a spinning wheel) and oscillatory motion (like a swing) are called periodic because they repeat their path over and over again at regular times.

🎯 Exam Tip: To explain this, first define periodic motion, then provide a clear example for both circular and oscillatory motion, showing how each repeats in a fixed time interval.

 

Question 4. Why are some length measuring instruments made of flexible material?
Answer: Not all objects have straight lengths that can be measured easily with a rigid ruler. Many objects have curved shapes or irregular perimeters, like the thickness of a tree trunk, the size of someone's chest, or a winding path. For such measurements, a rigid scale would be impractical. Flexible measuring instruments, such as tailor's tapes or measuring threads, are designed to bend and conform to these curved surfaces, allowing for accurate measurement of their true length or circumference.
In simple words: Some measuring tools are made flexible because not everything is straight. You need a bendy tape to measure around a tree, a person's chest, or a curved line.

🎯 Exam Tip: Explain that flexible materials are necessary for measuring non-linear or irregular shapes, as rigid scales can only accurately measure straight distances.

 

Question 6. What is oscillatory motion? Give some examples.
Answer: Oscillatory motion happens when an object moves back and forth around a fixed spot. This type of motion often involves a restoring force pulling the object back towards its resting position. Think of tree branches swaying in the wind, a child on a swing moving side to side, or the strings of a sitar vibrating. These are all good examples of oscillatory motion.
In simple words: Oscillatory motion is when something moves back and forth around a center point. Like a swing or tree branches moving in the wind.

🎯 Exam Tip: Remember that oscillatory motion is a type of repetitive motion, but specifically involves movement about a central equilibrium position.

Long Answer Type Questions

 

Question 1. Briefly explain the measurement systems of ancient India.
Answer: Ancient India had many ways to measure things. They used units like 'Angula,' which was the width of a finger, and also multiples of it, along with 'dhanusa' and 'yojana.' These units are found in old books and were used to measure items, buildings, and even cities. These traditional units show how early societies developed practical methods for daily measurements. Today, some traditional workers, like carpenters, still use the Angula. Also, old measuring tools that look like scales have been found in Harappan cities.
In simple words: Long ago, India used units like 'Angula' (finger width) for measuring. These old methods helped build cities and things we see today. Some people still use them.

🎯 Exam Tip: When discussing ancient measurement, highlight specific units (like Angula) and their practical applications in that era.

 

Question 2. What should be the correct position of the eyes while reading a scale? Explain by drawing a diagram.
Answer: When reading a scale, your eye must be directly above the mark you are checking. For example, if you measure a pencil, your eye should look straight down onto the exact point on the scale where the pencil ends. If you look from the left or right side, the measurement can appear wrong. This error is known as parallax error, and looking directly above helps eliminate it for precise measurements. This direct overhead view helps you get the most accurate reading.

🎯 Exam Tip: Always position your eye vertically above the mark being read on a scale to avoid parallax error and ensure accuracy.

 

Question 3. If the ends of the scale given to you for measurement are broken due to some reason, can you use it for measurement? Explain by giving an example.
Answer: Yes, even if a scale's ends are broken or the zero mark is unclear, you can still use it. To do this, start measuring from any clear full mark, like 1.0 cm. Then, read the mark at the other end of the object. This method helps in getting an accurate measurement even when the standard zero point is not available. Finally, subtract the starting mark from the ending mark to find the actual length. For instance, if you start at 1.0 cm and the object ends at 8.7 cm, its length is 8.7 cm - 1.0 cm, which is 7.7 cm.
In simple words: Yes, you can use a broken scale. Just start from a clear mark, like 1 cm, and subtract that starting number from the end number to get the real length.

🎯 Exam Tip: When using a broken scale, clearly state your starting point and the subtraction method to show accurate measurement technique.

 

Question 4. How are the symbols of units written? Explain.
Answer: Every measurement has two parts: a number and a unit. Units are shown using special symbols. These symbols are written in English and often look the same in Hindi. For length units like kilometer, meter, centimeter, and millimeter, their symbols (km, m, cm, mm) are usually in small letters and never get an 's' added to make them plural. Following these rules ensures that units are written consistently and understood universally in science. Also, you don't put a full stop after a unit symbol unless it's the end of a sentence. Always put a space between the number and its unit, for example, '10 m'.
In simple words: Measurements have a number and a unit (like 10 meters). Unit symbols (like m, cm, km) are usually small letters, don't use 's' for plural, and need a space before them.

🎯 Exam Tip: Always use lowercase for unit symbols (unless named after a person, like 'N' for Newton) and leave a space between the number and the unit.

 

Question 5. Can an object be stationary or moving in any situation? Explain by giving an example.
Answer: Yes, whether an object is still or moving depends entirely on your 'reference point.' This is the object or spot you compare it to. This concept of relative motion is fundamental to understanding how we perceive movement in the world. For instance, if you are inside a moving bus, you are still (stationary) relative to the bus itself. But if you think about a tree outside the bus, then both the bus and you, the passenger, are in motion compared to that tree. So, motion is always relative.
In simple words: An object can be still or moving depending on what you compare it to. A passenger in a bus is still compared to the bus, but moving compared to a tree outside.

🎯 Exam Tip: Clearly define the reference point in your explanation to accurately describe whether an object is in motion or at rest.

 

Question 6. What precautions should we take while measuring length?
Answer: To measure length correctly, keep these things in mind: 1. Always place the measuring scale right next to the object you are measuring, along its full length. 2. If the scale's ends are broken or the 'zero' mark is not clear, don't start from zero. Instead, start from any clear whole number mark, like 1 cm, and subtract this starting value from the final reading. 3. Position your eye directly above the point you are reading on the scale. These simple steps help ensure that your measurements are accurate and consistent every time. Looking from the side can make the measurement look different and incorrect.
In simple words: When measuring, place the scale close to the object. If the scale is broken, start from a clear mark and subtract. Always look straight down at the reading to avoid mistakes.

🎯 Exam Tip: List at least three key precautions for accurate length measurement, focusing on scale placement, zero error, and eye position.

Essay Type Questions

 

Question 1. Explain motion and describe its types.
Answer: Motion means an object changes its place compared to a fixed point over time. We can measure how much it moves (distance) and how fast (speed). Understanding these types of motion helps us describe and predict how objects move in the world around us. There are different kinds of motion: (i) Linear Motion: This is when an object moves in a straight line. Examples include soldiers marching or a fruit falling from a tree. (ii) Circular Motion: This happens when an object moves around a circle. A merry-go-round moving is an example. (iii) Oscillatory Motion: This is a back-and-forth movement around a fixed point. A child swinging on a swing shows oscillatory motion. (iv) Periodic Motion: This is when an object repeats its path or movement after a certain amount of time. Both circular motion (like a fan spinning) and oscillatory motion (like a clock pendulum) can be periodic if they keep repeating in regular cycles.
In simple words: Motion is when something changes its place. Types include moving in a straight line (linear), moving in a circle (circular), moving back and forth (oscillatory), and motion that repeats itself regularly (periodic).

🎯 Exam Tip: Define motion by referring to a change in position relative to a reference point, and give clear, distinct examples for each type of motion.

RBSE Class 6 Science Chapter 5 Notes - Measurement of Length and Motion

• People use a scale or measuring tape to measure the length of an object.
• The International System of Units (SI units) has been adopted by countries as standard units of measurement.
• The SI unit of length is metre. Its symbol is m.
• For measuring larger lengths, we use a larger unit called a kilometre (km) which is equal to 1000 metres. For smaller lengths, we use units such as centimetre or millimetre.
• For a curved line, measurements can be made with a flexible measuring tape or thread.
• When distance is given based on a fixed object or point, that point is called a reference point.
• An object is in motion if its position changes over time compared to a reference point.
• When an object moves along a straight line, its motion is called linear motion.
• When an object moves along a circular path, its motion is called circular motion.
• When an object moves back and forth around a fixed position, its motion is called oscillatory motion.
• If an object repeats its path after a fixed time, its motion is said to be periodic.