All questions of Measurement of Length and Motion for Class 6 Exam

The hands of a clock move in a circular path around the center of the clock face.

- A reference point is a stationary object used to determine the position of another object.
- For example, if you're watching a car move, a tree can serve as a reference point.
- If the car moves away from the tree, it is in motion; if it stays the same distance from the tree, it is at rest.
- This comparison allows us to understand the motion and position of objects relative to something fixed.

To avoid parallax error, the eye should be directly above the point of measurement.

Measurement ensures that we can communicate quantities effectively and consistently, which is crucial for tasks like buying fabric, cooking, or building structures.

A flexible measuring tape wraps around curved objects for accurate measurement.

Importance of Measurement in Daily Life
Measurement plays a crucial role in our daily activities, and option 'A' highlights its significance in communication. Here’s why measurement is essential:
Accurate Communication
- Measurements allow us to express quantities, sizes, and dimensions precisely.
- When we convey information, such as the length of a table or the amount of ingredients for a recipe, accuracy ensures that others understand our message correctly.
- For instance, saying "the book is 10 inches long" gives a clear idea of its size compared to vague phrases like "it's big."
Facilitates Planning and Organization
- In everyday tasks, measurements help in planning. For example, knowing the area of a room helps in purchasing the right amount of paint or flooring.
- When organizing events, measuring space for seating or decorations ensures that everything fits well.
Enhances Safety and Efficiency
- In cooking, using precise measurements of ingredients leads to successful recipes and prevents waste.
- In construction or DIY projects, accurate measurements ensure safety and structural integrity.
Supports Various Activities
- Measurement is vital in sports, health (e.g., measuring weight and height), and shopping (e.g., comparing prices per unit).
- It helps in making informed decisions based on quantitative data.
In conclusion, measurement is an integral part of daily life that enhances communication, planning, safety, and efficiency. By using precise measurements, we can ensure clarity and accuracy in our interactions and activities.

A reference point is a fixed point used to describe the position of an object, providing a basis for comparison.

Understanding Periodic Motion
Periodic motion refers to any motion that repeats itself at regular intervals of time. It is characterized by a cycle, which is a complete sequence of motions that returns to the starting point.
Why Option B is Correct
- The Earth rotating on its axis is a classic example of periodic motion:
- Regular Interval: The Earth takes approximately 24 hours to complete one full rotation.
- Predictable Cycle: This rotation causes day and night, which occur in a predictable pattern.
- Repetitive Nature: Every day, the Earth returns to the same position relative to the sun, fulfilling the criteria of periodicity.
Other Options Explained
- Option A: A car stopping at a signal
- This motion is not periodic as it does not repeat at regular intervals. The timing of the stops depends on traffic signals, which can vary.
- Option C: A person walking randomly
- Random walking does not follow a set pattern or cycle, making it non-periodic. The path taken is unpredictable.
- Option D: A book lying on a table
- The book is stationary and does not exhibit any motion, periodic or otherwise.
Conclusion
In conclusion, among the given options, the Earth's rotation on its axis (Option B) is the only example of periodic motion due to its consistent and repeating nature over a defined time frame.

Understanding the Standard SI Unit of Length
The standard SI (International System of Units) unit of length is the meter. This unit is fundamental in scientific measurements and serves as a basis for various applications across different fields.
Why the Meter?
- The meter is defined based on the distance light travels in a vacuum in a specific time interval.
- This definition, established in 1983, ensures that the meter is universally applicable and consistent.
Comparison with Other Units
- Inch: Primarily used in the United States and a few other countries, one inch equals 2.54 centimeters. It is not part of the SI system.
- Foot: Another non-SI unit, the foot is commonly used in the US and UK. One foot is equivalent to 0.3048 meters.
- Mile: A larger unit of length, one mile equals approximately 1,609.34 meters. It is also not part of the SI system and is mostly used in the US for measuring distances.
Importance of the SI System
- The SI system, which includes the meter as its base unit for length, provides a standardized framework for measurement that is recognized globally.
- This consistency is crucial for scientific research, engineering, and international trade, ensuring that measurements are understood universally.
Conclusion
In summary, the meter is the correct answer to the question about the standard SI unit of length. Its universal acceptance and precise definition make it a vital component of scientific measurement and international communication.

Explanation:

Oscillatory Motion:
When an object moves back and forth about a fixed position, it is known as oscillatory motion. This type of motion involves the object repeatedly moving between two points or positions.

Characteristics of Oscillatory Motion:
- The object moves to and fro around a central or equilibrium position.
- The motion is periodic, meaning it repeats at regular intervals.
- The object experiences acceleration towards the equilibrium position.

Examples of Oscillatory Motion:
- A swing moving back and forth.
- A pendulum swinging from side to side.
- A vibrating tuning fork.

Applications of Oscillatory Motion:
- Oscillatory motion is used in various devices such as clocks, metronomes, and tuning forks.
- It is also utilized in systems like springs and shock absorbers.
In conclusion, oscillatory motion involves the repeated movement of an object back and forth about a fixed position. This type of motion is characterized by its periodic nature and is commonly observed in everyday objects and devices.

Linear motion occurs when an object moves in a straight path, like a car on a road.

Understanding Length Measurement for Visually Challenged Individuals
Measuring length can be challenging for visually impaired individuals, but specialized tools and techniques make it possible. Among the options provided, using a special scale with raised markings is the most effective method.
Why Raised Markings are Effective
- Tactile Feedback: Raised markings allow individuals to feel the measurements with their fingers. This tactile feedback enables them to identify different lengths without needing to see the scale.
- Precision: Special scales are designed with clear, distinguishable markings. This precision ensures that users can accurately measure lengths, whether for educational purposes or daily tasks.
- Independence: Using a tactile scale empowers visually challenged individuals to measure length independently, fostering confidence and self-reliance in various activities.
Other Options Explained
- Digital Screen (Option A): While some digital measuring devices offer audio feedback, they may not be accessible for everyone and can require additional technology that might not be readily available.
- Asking Someone Else (Option C): This option relies on external help, which can limit the individual’s autonomy and may not always be practical in every situation.
- Guessing the Length (Option D): Guessing is the least accurate method and can lead to errors, making it unsuitable for tasks that require precision.
In conclusion, using a special scale with raised markings provides a reliable and efficient way for visually challenged individuals to measure length accurately and independently.

- The term "Angula" refers to the width of a finger and was a common unit of measurement in ancient India.
- It is approximately equal to 1.5 inches or 3.8 centimeters.
- Traditional craftsmen, such as carpenters and tailors, still utilize Angula for precise measurements, as it offers a practical and easily relatable standard.
- This reflects the continuity of ancient practices in modern times, especially in traditional trades where tools may be limited.

Curved lines can be accurately measured using a thread and then measuring the thread with a measuring tape.

The scale must be placed in contact with the object along its length for accurate measurement.

Understanding Pendulum Motion
A pendulum exhibits oscillatory motion, which is characterized by a repetitive back-and-forth movement around a central position.
What is Oscillatory Motion?
- Oscillatory motion refers to movements that occur in a regular pattern, typically around a specific equilibrium point.
- In the case of a pendulum, it swings to one side, then back through its central position, and swings to the opposite side.
How a Pendulum Works
- A pendulum consists of a weight (or bob) attached to a string or rod, allowing it to swing freely under the influence of gravity.
- When displaced from its resting position and released, the force of gravity pulls it back towards the central point, causing it to swing back and forth.
Key Characteristics of Pendulum Motion
- Regular Periodicity: The time taken for one complete cycle of motion (swinging to one side and back to the other) is constant, assuming no external forces act on it.
- Equilibrium Position: The central position is the point where the pendulum would hang if not disturbed, representing a state of rest.
- Energy Conversion: As the pendulum swings, gravitational potential energy converts to kinetic energy and vice versa, illustrating energy conservation.
Conclusion
The pendulum’s movement is a classic example of oscillatory motion, making it a fundamental concept in physics to study periodic phenomena. Understanding this motion helps in grasping more complex theories related to waves, vibrations, and oscillations.

Understanding Measurement with Body Parts
When we refer to measuring with body parts, we are talking about using physical features of our body to estimate lengths or distances. This method is often more relatable and can be easily applied in everyday situations. Let’s explore why option 'C' is the correct answer.
Examples of Measurement Tools
- a) Using a metre scale: This is a standard measuring tool that provides precise measurements in units such as centimeters and meters. It does not involve body parts.
- b) Using a weighing machine: This device measures weight, usually in kilograms or pounds, and is not related to body measurements.
- c) Using a handspan to measure a table: This is an example of measuring with body parts. A handspan is the distance from the tip of the thumb to the tip of the little finger when the hand is fully stretched. It is a practical way to estimate the size of an object using one’s own body.
- d) Using a thermometer: A thermometer is used to measure temperature, which is unrelated to body part measurements.
Why Option 'C' is Correct
- Personal Reference: The handspan is a body part that individuals can easily use to measure objects around them, making it a personal and accessible method of measurement.
- Estimating Lengths: Since everyone's handspan is different, it provides a rough estimate rather than a precise measurement. This is typically acceptable in casual settings.
In summary, option 'C' is the only choice that represents measurement using a body part, while the other options involve tools that provide standardized measurements.

The metre is the standard unit of length in the SI system.

Traditional methods varied greatly because people's body parts differ in size, leading to inconsistencies in measurements.

Viewing the scale from directly above avoids parallax error and ensures correct readings.

A kilometre is equal to 1000 metres and is used to measure large distances, such as between cities.

Kilometres are used to measure long distances, such as the distance between cities.