Chapter 5: Measurement of Length and Motion
Comprehensive Exercise (Made for exam preparation)
Class 6 Science
Question 1: Choose the correct option (Multiple Choice Questions):
1. What is the Standard International (SI) unit of length?
Answer: (B) Metre.
2. A child playing on a swing is an example of which type of motion?
Answer: (C) Oscillatory motion.
3. Which of the following units is most suitable for measuring the distance between two cities like Delhi and Lucknow?
Answer: (D) Kilometre.
4. When an object moves along a circular path (like a merry-go-round), its motion is called:
Answer: (B) Circular motion.
5. What do we essentially need to decide whether an object is in motion or at rest?
Answer: (B) A reference point.
Question 2: Fill in the blanks with the appropriate words:
- 1. When an object moves to and fro about some fixed position, its motion is called oscillatory motion.
- 2. If an object repeats its path after a fixed interval of time, its motion is said to be periodic in nature.
- 3. The distance between your school and home is 1.5 km, which is equal to 1500 metres.
- 4. When a heavy box is pushed across the floor, it generally moves in a straight line, showing linear motion.
- 5. If the position of an object is not changing with time with respect to a reference point, the object is at rest.
Question 3: State whether the following statements are True or False:
- 1. A stone dropped from a certain height falls in a circular motion.
Answer: False (It moves in a linear motion). - 2. Passengers sitting inside a moving bus are at rest with respect to each other.
Answer: True. - 3. The thickness of a small coin should be measured in kilometres.
Answer: False (It should be measured in millimetres). - 4. Both circular and oscillatory motions are periodic in nature.
Answer: True. - 5. You can accurately measure the length of a curved line using only a straight plastic scale.
Answer: False (A thread is needed to trace the curve first).
Question 4: Match the items in Column 'A' with the correct items in Column 'B':
| Column 'A' | Column 'B' |
|---|---|
| 1. Distance between two distant cities | (a) Metre |
| 2. Thickness of a coin | (b) Millimetre |
| 3. Length of an eraser | (c) Oscillatory motion |
| 4. Length of a school ground | (d) Centimetre |
| 5. Motion of a plucked metal strip | (e) Kilometre |
Correct Matches:
- 1 → (e) Kilometre
- 2 → (b) Millimetre
- 3 → (d) Centimetre
- 4 → (a) Metre
- 5 → (c) Oscillatory motion
Question 5: Classification. Classify the following examples of motion into "Linear Motion" and "Oscillatory Motion":
Items: 1. A pendulum moving to and fro, 2. An orange dropping from a tree, 3. A child playing on a swing, 4. Students doing march-past in a straight line, 5. A thin metal strip pressed and released to move up and down.
- Linear Motion: 2. An orange dropping from a tree, 4. Students doing march-past in a straight line.
- Oscillatory Motion: 1. A pendulum moving to and fro, 3. A child playing on a swing, 5. A thin metal strip pressed and released to move up and down.
Question 6: Answer the following questions in one sentence:
1. What does the term 'Reference point' mean?
Answer: A reference point is a fixed place or object used to determine whether another object is in motion or at rest.
2. How would you measure the length of a curved boundary of a leaf?
Answer: We can trace the curved boundary using a thread and then measure the length of that thread using a standard scale.
3. Give one example of circular motion from your surroundings.
Answer: The motion of a moving merry-go-round or the blades of a moving fan are examples of circular motion.
4. What type of motion does an eraser show when tied to a thread and whirled around by hand?
Answer: The eraser shows circular motion.
5. How many centimetres are there in one metre?
Answer: There are 100 centimetres in one metre.
Question 7: Give scientific reasons:
1. Reason: We use kilometres instead of metres to measure the distance between two cities.
Answer: Because cities are very far apart, and measuring such large distances in small units like metres or centimetres is highly inconvenient; kilometre is a larger and more suitable unit.
2. Reason: A stretchable rubber cannot be used to make a standard measuring scale.
Answer: Because stretchable rubber changes its length when pulled, so it will give different measurements for the same object every time, making it inaccurate.
3. Reason: A passenger in a moving bus is considered both 'in motion' and 'at rest' at the same time.
Answer: Because motion is relative; the passenger is in motion with respect to a tree outside (reference point), but at rest with respect to the co-passengers inside the bus.
4. Reason: The motion of a swing is called periodic motion.
Answer: Because the swing moves to and fro and repeats its exact path after a fixed interval of time, which is the defining characteristic of periodic motion.
5. Reason: We need a standard unit (SI unit) of length for measurement.
Answer: Because non-standard methods like using handspans or footsteps vary from person to person; standard units like the metre ensure that measurements remain the same for everyone globally.
Question 8: Answer the following questions in short (2-3 sentences):
1. How do you decide whether an object is at rest or in motion?
Answer: We decide this by observing the object with respect to a reference point. If the position of the object changes over time relative to the reference point, it is in motion; if it does not change, it is at rest.
2. Distinguish between Linear motion and Circular motion with examples.
Answer: When an object moves perfectly along a straight line (e.g., a heavy box being pushed, an apple falling), it is linear motion. When an object moves along a circular path (e.g., a merry-go-round, a whirled stone), it is circular motion.
3. What is oscillatory motion? Give two examples.
Answer: When an object moves to and fro about some fixed central position, it is called oscillatory motion. Examples: A swinging pendulum and a child playing on a swing.
4. Suppose you want to measure the thickness of a single page of your science textbook. How will you do it?
Answer: A single page is too thin to measure directly. I will measure the thickness of 100 pages together using a millimetre scale, and then divide the total thickness by 100 to find the exact thickness of a single page.
5. Explain why both circular and oscillatory motions are considered 'periodic'.
Answer: A motion is periodic if it repeats itself after a fixed time. In a circular motion (like a merry-go-round) and in an oscillatory motion (like a pendulum), the objects repeatedly cover the exact same path in equal time intervals, so both are periodic.