Motion and Measurement of Distances Class 6 Questions and Answers

📏 Motion and Measurement of Distances Class 6 Questions and Answers

NCERT Chapter 10 with Detailed Solutions

Master Motion and Measurement of Distances for Class 6 Science with comprehensive questions and answers covering SI units, types of motion, measuring instruments, and correct measurement techniques. Each answer is explained in simple, student-friendly language for CBSE exams.

📘 BACK TO ALL CHAPTERS

⚡

Motion and Measurement of Distances — Questions & Answers

NCERT Class 6 Science Chapter 10

Question 1

What is motion?

✅ Answer:

Motion is the change in position of an object with time with respect to its surroundings.

Question 2

Name the SI unit of length.

✅ Answer:

The SI unit of length is the metre (m).

Question 3

How many centimetres are there in 1 metre?

✅ Answer:

There are 100 centimetres in 1 metre.

Question 4

What is rectilinear motion?

✅ Answer:

Rectilinear motion is the motion of an object along a straight line path. Example: a car moving on a straight road.

Question 5

Define circular motion.

✅ Answer:

Circular motion is the motion of an object along a circular path, where the distance from the centre remains constant. Example: a fan blade.

Question 6

What is periodic motion?

✅ Answer:

Periodic motion is the motion that repeats itself after a fixed interval of time. Example: the swinging of a pendulum.

Question 7

What is the name of the device used to measure length?

✅ Answer:

A metre scale is a common device used to measure length.

Question 8

What are the two types of motion based on the path?

✅ Answer:

The two types of motion based on the path are rectilinear motion (along a straight line) and circular motion (along a circular path).

Question 9

Give an example of an object showing multiple motions.

✅ Answer:

A rolling ball shows both rectilinear and rotational motion.

Question 10

What is the need for standard units of measurement?

✅ Answer:

Standard units are needed for uniformity and accuracy in measurements across the world.

Question 11

Name any two ancient units of length.

✅ Answer:

Two ancient units of length are cubit and handspan.

Question 12

Why is it important to place the scale correctly while measuring?

✅ Answer:

Placing the scale correctly ensures accurate measurement with the zero mark at the start of the object.

Question 13

What is the SI unit of time?

✅ Answer:

The SI unit of time is the second (s).

Question 14

What is the motion of a pendulum called?

✅ Answer:

The motion of a pendulum is called periodic motion (or oscillatory motion).

Question 15

What is the distance between two cities measured in?

✅ Answer:

The distance between two cities is measured in kilometres (km).

Question 16

How many millimetres are there in 1 centimetre?

✅ Answer:

There are 10 millimetres in 1 centimetre.

Question 17

Name the motion of the Earth around the Sun.

✅ Answer:

The motion of the Earth around the Sun is circular and periodic motion.

Question 18

What is the full form of SI?

✅ Answer:

The full form of SI is International System of Units.

Question 19

Which motion is shown by a moving potter's wheel?

✅ Answer:

A moving potter's wheel shows rotational motion.

Question 20

Give one example of a natural unit of length.

✅ Answer:

Foot is an example of a natural (ancient) unit of length.

Question 21

What is the correct way to measure a curved line?

✅ Answer:

A curved line is measured by placing a thread along the curve and then measuring the thread's length on a scale.

Question 22

What is the motion of a train on a straight track?

✅ Answer:

The motion of a train on a straight track is rectilinear motion.

Question 23

What is the SI unit of mass?

✅ Answer:

The SI unit of mass is the kilogram (kg).

Question 24

Which type of motion is shown by the strings of a guitar?

✅ Answer:

The strings of a guitar show periodic motion (or oscillatory motion).

Question 25

What is the name of the motion of a body moving along a circular path?

✅ Answer:

The motion of a body moving along a circular path is called circular motion.

Question 26

Why can't we use handspan as a standard unit?

✅ Answer:

Handspan varies from person to person, so it is not a reliable or uniform unit of measurement.

Question 27

What is the approximate distance between Delhi and Mumbai measured in?

✅ Answer:

The distance between Delhi and Mumbai is measured in kilometres (km).

Question 28

Which instrument is used to measure the girth of a tree?

✅ Answer:

A measuring tape is used to measure the girth of a tree.

Question 29

What is the motion of a child on a swing?

✅ Answer:

The motion of a child on a swing is oscillatory (periodic) motion.

Question 30

What is the unit used to express the length of a pencil?

✅ Answer:

The length of a pencil is usually measured in centimetres (cm).

Question 1

Why do we need standard units for measurement?

✅ Answer:

We need standard units because non-standard units like handspan, foot, or cubit vary from person to person. This variation causes confusion and inaccuracy in measurement. Standard units like metre, centimetre, and kilometre are uniform worldwide, ensuring that measurements are accurate and can be understood by everyone.

Question 2

What is the difference between rectilinear motion and circular motion?

✅ Answer:

Rectilinear motion: The object moves along a straight line path. Example: a car moving on a straight road.

Circular motion: The object moves along a circular path, and the distance from the centre remains constant. Example: the motion of a fan blade.

Question 3

How can you measure the length of a curved line?

✅ Answer:

To measure a curved line, follow these steps:

Place a thread along the curve, following its shape.
Mark the thread where the curve starts and ends.
Now straighten the thread and measure its length with a metre scale.

This gives the accurate length of the curved line.

Question 4

What are the different types of motion? Give one example of each.

✅ Answer:

1. Rectilinear motion: Motion along a straight line. Example: A car moving on a straight road.

2. Circular motion: Motion along a circular path. Example: Motion of a fan blade.

3. Periodic motion: Motion that repeats after a fixed time interval. Example: Swinging of a pendulum.

4. Rotational motion: Motion around an axis. Example: Spinning of a top.

Question 5

Why is it important to have a standard unit of measurement?

✅ Answer:

A standard unit of measurement is important because:

It ensures uniformity in measurements everywhere in the world.
It allows for accurate communication of measurement results.
It is reliable and consistent — everyone using the same standard gets the same result.

Question 6

What is the difference between distance and displacement?

✅ Answer:

Distance: The total path covered by a moving object. It is a scalar quantity and is always positive.

Displacement: The shortest straight-line distance between the initial and final positions of an object. It is a vector quantity and can be positive, negative, or zero.

Question 7

Explain the correct method to measure the length of an object using a scale.

✅ Answer:

To measure the length of an object using a scale:

Place the zero mark of the scale at one end of the object.
Ensure the scale is parallel to the object.
Keep your eye directly above the point where the object ends.
Read the mark that aligns with the other end of the object.

If the zero mark is broken, start from another full mark and subtract.

Question 8

What are the ancient units of measurement? Why were they replaced?

✅ Answer:

Ancient units of measurement include foot, cubit, handspan, yard, and pace. They were based on body parts of humans.

They were replaced because:

They varied from person to person.
They lacked uniformity and accuracy.
They could not be used for reliable international communication.

Question 9

What is a simple pendulum? What type of motion does it show?

✅ Answer:

A simple pendulum consists of a small metallic ball (bob) suspended from a fixed point by a thread. When displaced slightly and released, it moves to and fro about a fixed point.

A pendulum shows periodic motion (also called oscillatory motion) because it repeats its motion after a fixed interval of time.

Question 10

Convert 5 kilometres into metres.

✅ Answer:

We know that 1 kilometre = 1000 metres.

So, 5 kilometres = 5 × 1000 = 5000 metres.

Question 11

What are the precautions to be taken while measuring length?

✅ Answer:

Precautions while measuring length:

Place the scale along the object, not at an angle.
Use the zero mark as the starting point. If broken, start from a full mark and subtract.
Keep the eye vertically above the reading point to avoid parallax error.
Ensure the scale is not worn out at the edges.

Question 12

Give examples of objects that show more than one type of motion.

✅ Answer:

Examples of objects showing multiple motions:

A rolling ball shows rectilinear motion (moving forward) and rotational motion (spinning).
A cycle wheel shows circular motion (wheel rotating) and rectilinear motion (bicycle moving forward).
A drilling machine shows rotational motion and rectilinear motion (moving downward while rotating).

Question 13

What is the difference between rotational and circular motion?

✅ Answer:

Circular motion: An object moves along a circular path, and the entire object moves around the centre. Example: The motion of the Earth around the Sun.

Rotational motion: An object spins about its own axis. Example: The motion of a spinning top or the Earth rotating on its axis.

Question 14

What is the importance of measurement in our daily life?

✅ Answer:

Measurement is important in daily life because:

We need to measure clothes, food, and materials for buying and selling.
In construction, accurate measurement ensures proper building.
In science and medicine, precise measurements are essential for experiments and treatments.
It helps in navigation and travel to know distances.

Question 15

Explain why a rolling ball is said to have two types of motion.

✅ Answer:

A rolling ball has two types of motion:

Rectilinear motion: The ball moves forward in a straight line.
Rotational motion: The ball spins about its own axis as it moves.

Since both motions happen simultaneously, the rolling ball is said to have multiple motions.

Question 1

Explain the historical development of measurement systems and the need for standard units.

✅ Answer:

Historical Development of Measurement:

In ancient times, people used body parts as units of measurement:

Foot: Length of a human foot
Cubit: Distance from elbow to fingertip
Handspan: Width of a stretched hand
Yard: Distance from chin to outstretched arm

Problems with Ancient Units:
These units varied from person to person. A tall person's foot was longer than a short person's foot. This caused confusion in trade and construction.

Development of Standard Units:
To solve this problem, the International System of Units (SI) was developed. The metre was chosen as the standard unit of length. Now, 1 metre is defined as the distance travelled by light in vacuum in a specific fraction of a second.

Why Standard Units Are Important:

Uniformity: A metre is a metre everywhere in the world.
Accuracy: Scientific experiments require precise measurements.
Communication: Scientists, engineers, and traders worldwide can understand each other.
Comparison: Measurements can be compared easily.

Question 2

Describe the different types of motion with examples. How can an object have more than one type of motion?

✅ Answer:

Types of Motion:

1. Rectilinear Motion:
Motion along a straight line. Example: A car moving on a straight road, a stone falling from a height.

2. Circular Motion:
Motion along a circular path where the distance from the centre remains constant. Example: Motion of a fan blade, movement of the Earth around the Sun.

3. Periodic Motion:
Motion that repeats itself after a fixed interval of time. Example: Swinging of a pendulum, strings of a guitar vibrating.

4. Rotational Motion:
Motion where an object spins about its own axis. Example: Spinning of a top, rotation of the Earth on its axis.

Objects with Multiple Motions:
Some objects show more than one type of motion at the same time. For example:

A rolling ball shows both rectilinear motion (moving forward) and rotational motion (spinning).
A cycle wheel shows circular motion (wheel rotating) and rectilinear motion (bicycle moving forward).
A drilling machine shows rotational motion (drill rotating) and rectilinear motion (moving downward).

This happens because different parts of the object may be moving differently, or the same object may have multiple simultaneous movements.

Question 3

Explain how to measure the length of a curved line with the help of an activity.

✅ Answer:

Activity to Measure a Curved Line:

Materials needed:

A curved line drawn on paper (like a map road)
A thread
A metre scale
A pencil

Steps:

Place one end of the thread at the starting point of the curved line.
Carefully lay the thread along the curve, following its shape.
When you reach the end of the curve, mark that point on the thread.
Now straighten the thread and place it along a metre scale.
Measure the length between the two marked points.

Result:
The length on the scale gives the accurate length of the curved line.

Why This Method Works:
The thread takes the shape of the curve. When straightened, its length equals the length of the curve. This is the most accurate way to measure curved lines.

Question 4

What is the importance of measurement in science and everyday life? Give examples.

✅ Answer:

Importance of Measurement:

1. In Science:

Scientists need accurate measurements for experiments.
In physics, we measure length, time, mass, temperature, etc.
In chemistry, precise quantities of chemicals are measured.
In biology, the size of cells and organisms is measured.

2. In Daily Life:

We measure cloth before buying clothes.
We measure ingredients while cooking.
We measure distance while travelling.
We measure temperature when we are sick.
We measure weight of vegetables and fruits.

3. In Trade and Commerce:

Goods are sold by weight, length, or volume.
Standard measurements prevent cheating.

4. In Construction:

Buildings, roads, and bridges require precise measurements.
Incorrect measurement can cause accidents.

Conclusion:
Measurement is essential for science, trade, construction, and everyday activities. Standard units ensure accuracy and uniformity across the world.

Question 5

Describe an experiment to show that a pendulum shows periodic motion.

✅ Answer:

Experiment to Show Periodic Motion of a Pendulum:

Materials needed:

A small metallic ball (bob)
A thread (about 1 metre long)
A stand
A stopwatch

Procedure:

Tie the bob to one end of the thread.
Attach the other end to the stand.
Displace the bob slightly to one side and release it.
Observe the motion. The bob moves to and fro about a fixed point.
Using the stopwatch, measure the time taken for 10 oscillations.
Divide by 10 to find the time period of one oscillation.

Observation:
The pendulum takes the same time for each oscillation. The motion repeats after equal intervals of time.

Conclusion:
The pendulum shows periodic motion because it repeats its to-and-fro movement after a fixed interval of time (the time period).

Question 6

Why are standard units important? Explain with examples from different fields.

✅ Answer:

Why Standard Units Are Important:

1. Uniformity:
If everyone uses the same unit, measurements are the same everywhere. A metre in India is the same as a metre in America.

2. Accuracy:
Standard units are precisely defined, allowing accurate measurements. Non-standard units like handspan vary from person to person.

3. Communication:
Scientists and engineers worldwide can share data confidently when using standard units.

Examples from Different Fields:

Science: Experiments require exact amounts of chemicals measured in grams or millilitres.
Medicine: Medicines are prescribed in milligrams, requiring precise measurement.
Construction: Buildings require exact measurements of length and width.
Trade: Gold is sold by grams, cloth by metres.
Travel: Distances between cities are measured in kilometres.

Conclusion:
Standard units are the backbone of accurate measurement and global communication. Without them, science, trade, and construction would be chaotic.

Question 7

Explain the correct way to use a metre scale for measuring length. What precautions should be taken?

✅ Answer:

Correct Way to Use a Metre Scale:

Steps:

Place the object on a flat surface.
Place the zero mark of the scale at one end of the object.
Ensure the scale is parallel to the object, not tilted.
Keep your eye vertically above the point where the object ends.
Read the mark that aligns with the other end of the object.
If the zero mark is broken, start from a full mark (like 1 cm) and subtract 1 cm from the reading.

Precautions:

Do not tilt the scale: It should be parallel to the object.
Use the correct zero: If the edge is worn, use another full mark.
Avoid parallax error: Keep your eye directly above the reading point.
Check the scale: Do not use a broken or worn-out scale.
Measure from zero: Always start from the zero mark unless it is broken.

Conclusion:
Correct use of a metre scale ensures accurate measurements, which is essential for science experiments and daily activities.

Question 8

What is the difference between distance and displacement? Which one is always positive?

✅ Answer:

Distance:

The total path length covered by a moving object.
It is a scalar quantity — it has only magnitude, no direction.
It is always positive (or zero if no motion).
It does not depend on the direction of motion.

Displacement:

The shortest straight-line distance between the initial and final positions.
It is a vector quantity — it has both magnitude and direction.
It can be positive, negative, or zero.
It depends on the direction of motion.

Example:
If you walk 10 metres east and then 10 metres west:

Distance = 20 metres (total path covered)
Displacement = 0 metres (you are back at the starting point)

Conclusion:
Distance is always positive, while displacement can be positive, negative, or zero.

Question 9

Describe the evolution of transport from ancient times to modern times. How did measurement play a role?

✅ Answer:

Evolution of Transport:

1. Ancient Times:

People walked on foot.
Animals like horses, oxen, and camels were used for transport.
Boats were used to travel on water.

2. Invention of the Wheel:

The wheel was a major invention (around 3500 BCE).
Wheeled carts and chariots were developed.

3. Steam Engine:

In the 18th century, the steam engine was invented.
Steam-powered trains and ships made travel faster.

4. Modern Times:

Automobiles (cars, buses) were invented in the 19th century.
Aeroplanes allowed air travel in the 20th century.
Spacecraft now travel to outer space.

Role of Measurement:

Accurate measurement of distance was needed for navigation.
Measurement of time helped in planning journeys.
Standard units ensured that maps and trade routes were accurate.
Modern vehicles rely on precise measurements for design and safety.

Question 10

Define the SI unit of length. What are its multiples and submultiples? How are they related?

✅ Answer:

SI Unit of Length:
The SI unit of length is the metre (m). It is defined as the distance travelled by light in vacuum in 1/299,792,458 of a second.

Multiples and Submultiples of Metre:

Multiples (larger units):

1 kilometre (km) = 1000 metres
1 hectometre (hm) = 100 metres
1 decametre (dam) = 10 metres

Submultiples (smaller units):

1 decimetre (dm) = 0.1 metre (1/10 m)
1 centimetre (cm) = 0.01 metre (1/100 m)
1 millimetre (mm) = 0.001 metre (1/1000 m)

Relationships:

1 km = 1000 m
1 m = 100 cm
1 cm = 10 mm
Therefore, 1 m = 1000 mm

Conclusion:
The metre is the standard unit of length. Multiples and submultiples allow us to measure both very large and very small distances conveniently.

📘 Quick Revision: Motion and Measurement of Distances

Motion: Change in position of an object with time.
Types of Motion: Rectilinear (straight line), Circular (circular path), Periodic (repeats), Rotational (spinning).
SI Unit of Length: Metre (m). 1 m = 100 cm = 1000 mm. 1 km = 1000 m.
Ancient Units: Foot, cubit, handspan, yard — varied from person to person.
Standard Units: Needed for uniformity, accuracy, and global communication.
Measuring Curved Lines: Use a thread along the curve, then measure on a scale.
Precautions: Place scale parallel, use zero mark, keep eye above reading point.
Simple Pendulum: Shows periodic motion.