Measurement of Length and Motion — Class 6 Science NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 6 Science chapter "Measurement of Length and Motion" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 6 Science chapter "Measurement of Length and Motion" — 8 important questions with detailed answers for CBS…
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NCERT Solutions for Class 6 Science — Measurement of Length and Motion. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Measurement of Length and Motion — All 8 Questions Solved
Q1. What is measurement and why is it important?
Measurement is the process of finding the size, length, or quantity of something using standard units. It is important for accurate communication and comparison of physical quantities.
Q2. What are SI units and name the SI unit of length.
SI units are international standard units used worldwide for measurement. The SI unit of length is meter (m).
Q3. What are the common units for measuring length and their conversions?
Common units are:
- 1 kilometer (km) = 1000 meters
- 1 meter (m) = 100 centimeters
- 1 centimeter (cm) = 10 millimeters
Q4. Define motion and give examples.
Motion is change in position of an object with respect to a reference point or time. Examples: a moving car, flying bird, running person, rolling ball.
Q5. What are the main types of motion?
Main types are:
- Rectilinear motion (straight-line motion)
- Circular motion (motion in a circle)
- Oscillatory motion (back and forth motion)
Q6. What is speed and how is it calculated?
Speed is the distance covered by an object in a given time. It is calculated as:
Speed = Distance traveled / Time taken
Q7. What is the difference between distance and displacement?
Distance is the total path length covered by an object, while displacement is the shortest straight-line distance between starting and ending points with direction.
Q8. Name common measuring instruments and their uses.
Common instruments are:
- Ruler/scale (measure length in centimeters)
- Measuring tape (measure large distances)
- Speedometer (measure speed of vehicle)
- Odometer (measure distance traveled by vehicle)
Measurement of Length and Motion — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. What is the standard unit of length in the International System of Units (SI)?
- A. kilogram
- B. second
- C. meter
- D. liter
Answer: C. meter — The meter is the standard SI unit for measuring length. Kilogram is for mass, second for time, and liter for volume.
MCQ 2. Which of these was NOT a standard unit of length used in ancient times?
- A. Handspan
- B. Cubit
- C. Foot
- D. Centimeter
Answer: D. Centimeter — Handspan, Cubit, and Foot were non-standard units based on body parts used in ancient times, whereas the centimeter is a modern standard unit of length.
MCQ 3. When using a ruler to measure the length of an object, what is the correct way to position your eye?
- A. From the left side of the mark
- B. From the right side of the mark
- C. Vertically above the mark
- D. Any position is fine
Answer: C. Vertically above the mark — Positioning the eye vertically above the mark helps avoid parallax error, ensuring an accurate reading of the measurement.
MCQ 4. How many centimeters are there in 5 meters?
- A. 50 cm
- B. 500 cm
- C. 5000 cm
- D. 5 cm
Answer: B. 500 cm — Since 1 meter is equal to 100 centimeters, 5 meters will be 5 x 100 = 500 centimeters.
MCQ 5. Which type of motion does a car moving on a straight road exhibit?
- A. Circular motion
- B. Rotational motion
- C. Rectilinear motion
- D. Periodic motion
Answer: C. Rectilinear motion — Rectilinear motion is the motion of an object along a straight line. A car on a straight road moves in a straight line.
MCQ 6. What kind of motion does the tip of a fan blade show when the fan is switched on?
- A. Rectilinear motion
- B. Circular motion
- C. Vibratory motion
- D. Rotational motion
Answer: B. Circular motion — The tip of a fan blade moves along a circular path around the center of rotation, demonstrating circular motion.
MCQ 7. A child riding a bicycle on a straight road. Which of the following statements about the motion of the bicycle wheel is true?
- A. It shows only rectilinear motion
- B. It shows only circular motion
- C. It shows both rectilinear and rotational motion
- D. It shows both rectilinear and circular motion
Answer: C. It shows both rectilinear and rotational motion — The wheel of the bicycle rotates about its axis (rotational motion) and simultaneously moves forward along a straight path with the bicycle (rectilinear motion).
MCQ 8. Which of these objects exhibits periodic motion?
- A. A stone falling from a height
- B. A car moving on a highway
- C. A pendulum of a clock
- D. A ball rolling down a ramp
Answer: C. A pendulum of a clock — Periodic motion is motion that repeats itself after a fixed interval of time. A pendulum swings back and forth, repeating its motion regularly.
MCQ 9. A student measures the length of a table as 150 cm. If they want to express this in meters, what would be the correct measurement?
- A. 0.15 m
- B. 1.5 m
- C. 15 m
- D. 1500 m
Answer: B. 1.5 m — Since 100 centimeters make 1 meter, to convert centimeters to meters, you divide by 100. So, 150 cm / 100 = 1.5 meters.
MCQ 10. What kind of motion does a spinning top show?
- A. Rectilinear motion
- B. Circular motion
- C. Rotational motion
- D. Vibratory motion
Answer: C. Rotational motion — A spinning top rotates around its own fixed axis, which is an example of rotational motion.
MCQ 11. What is parallax error in measurement?
- A. Error due to an incorrect starting point on the scale
- B. Error due to a broken measuring scale
- C. Error due to looking at the scale from an angle
- D. Error due to a faulty measuring instrument
Answer: C. Error due to looking at the scale from an angle — Parallax error occurs when the eye is not positioned directly perpendicular to the marking on the scale, leading to an inaccurate reading.
MCQ 12. Imagine a person sitting on a moving train. Relative to the ground, the person is in motion. But relative to the train itself, what is the person's state?
- A. In motion
- B. At rest
- C. In circular motion
- D. In periodic motion
Answer: B. At rest — An object can be in motion relative to one reference point and at rest relative to another. The person is not moving with respect to the train compartment they are sitting in.
MCQ 13. Which instrument would be most suitable to measure the length of a small pencil box accurately?
- A. Measuring tape
- B. Ruler
- C. Kilometer counter
- D. Handspan
Answer: B. Ruler — A ruler is ideal for measuring short lengths like a pencil box accurately, typically up to 30 cm. A measuring tape is for longer lengths, and a kilometer counter is for very long distances.
MCQ 14. A swing in a park moves back and forth. What type of motion does it exhibit?
- A. Rectilinear motion
- B. Rotational motion
- C. Periodic motion
- D. Circular motion
Answer: C. Periodic motion — The swing repeats its back-and-forth movement after a fixed interval of time, which is characteristic of periodic motion.
MCQ 15. The distance between two cities is usually expressed in which unit?
- A. Centimeters
- B. Meters
- C. Kilometers
- D. Millimeters
Answer: C. Kilometers — Kilometers are used to measure large distances, such as the distance between cities, because they represent 1000 meters, making the numbers manageable.
MCQ 16. Which of the following is the standard unit for measuring length in the SI system?
- A. Centimeter
- B. Meter
- C. Kilometer
- D. Millimeter
Answer: B. Meter — The International System of Units (SI) defines the meter as the basic unit of length. Other units like centimeter, kilometer, and millimeter are multiples or submultiples of the meter.
MCQ 17. Which of these is NOT a standard unit of length?
- A. Handspan
- B. Centimeter
- C. Meter
- D. Kilometer
Answer: A. Handspan — Handspan is a non-standard unit of length because its size varies from person to person, leading to inconsistent measurements. Centimeter, meter, and kilometer are standard units.
MCQ 18. 1 kilometer is equal to how many meters?
- A. 10 meters
- B. 100 meters
- C. 1000 meters
- D. 10000 meters
Answer: C. 1000 meters — A kilometer is a larger unit of length, and 'kilo' means a thousand. Therefore, 1 kilometer is equal to 1000 meters.
MCQ 19. What is the correct way to place a scale to measure the length of an object?
- A. Hold it slanted against the object
- B. Place it far away from the object
- C. Place it along the length of the object, with its zero mark coinciding with one end
- D. Start measuring from any mark on the scale
Answer: C. Place it along the length of the object, with its zero mark coinciding with one end — For accurate measurement, the scale should be placed precisely along the length of the object, and measurement must begin from its zero mark.
MCQ 20. Which method is best for measuring the length of a curved line?
- A. Using a standard ruler directly
- B. Using a measuring tape directly
- C. Using a thread or string and then measuring the thread's length
- D. Using a compass
Answer: C. Using a thread or string and then measuring the thread's length — A ruler or measuring tape cannot bend to follow a curved line accurately. A thread can be laid along the curve, straightened, and then measured with a ruler for accuracy.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.