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Q1. The process of finding the size, length, mass, volume or any other physical quantity of an object is called:
Measurement is the process of finding the value of a physical quantity like length, mass, time or temperature. It helps us express the size or amount of something in numbers. Measurement is essential in our daily life, from buying cloth to cooking food.
Q2. The standard system of measurement used all over the world is called:
The SI system (International System of Units) is the standard system of measurement used all over the world. It was established to have a uniform system for scientific and commercial purposes. This system makes it easy to share and compare measurements globally.
Q3. The SI unit of length is the:
The SI unit of length is the metre, which is represented by the symbol ‘m’. It is used to measure distances, heights and lengths of objects. Other units like centimetre, kilometre and millimetre are derived from the metre.
Q4. The SI unit of mass is the:
The SI unit of mass is the kilogram, represented by ‘kg’. It is used to measure the amount of matter in an object. The kilogram is one of the base units of the SI system and is defined by a physical standard.
Q5. The SI unit of time is the:
The SI unit of time is the second, represented by ‘s’. It is used to measure the duration of events. The second is one of the base units of the SI system and is defined using the vibrations of atoms in a cesium clock.
Q6. A fixed point or an object used to determine the position of another object is called a:
A reference point is a fixed point or object that is used to determine the position of another object. For example, when we say a car is 5 kilometres away from the school, the school is the reference point. A reference point helps us describe the location of an object.
Q7. The change in position of an object with respect to a reference point over time is called:
Motion is the change in position of an object with respect to a reference point over time. An object is said to be in motion if its position changes relative to a fixed point. For example, a moving car is in motion because its position changes with respect to the road.
Q8. An object is said to be at rest if:
An object is said to be at rest if it does not change its position with respect to a reference point over time. For example, a book lying on a table is at rest because it does not move from its place. Rest and motion are relative, depending on the reference point chosen.
Q9. The movement of a car on a straight road is an example of:
Linear motion is the movement of an object in a straight line. A car moving on a straight road is a classic example of linear motion. In linear motion, the object moves along a straight path.
Q10. The movement of the hands of a clock is an example of:
Circular motion is the movement of an object along a circular path. The hands of a clock move in a circle around the centre of the clock. This is an example of circular motion.
Q11. The to and fro movement of a pendulum is an example of:
Periodic motion is the movement of an object that repeats itself after a fixed interval of time. The swinging of a pendulum is a perfect example of periodic motion because it repeats its swing at regular intervals. This property makes it useful for measuring time.
Q12. The rotation of the Earth on its axis is an example of:
The rotation of the Earth is an example of both circular and periodic motion. It moves in a circular path around its axis and this motion repeats every 24 hours. This periodic nature is what gives us day and night.
Q13. The distance between two points is always measured in:
Distance is measured in units of length, and the SI unit of length is the metre. Whether we measure the distance between two cities or the length of a table, we use metres (or derived units like kilometres or centimetres). Distance tells us how far apart two points are.
Q14. The SI unit of length, the metre, was originally defined as:
The metre was originally defined in 1791 as one ten-millionth of the distance from the Equator to the North Pole along the meridian through Paris. This definition was later replaced by more precise definitions based on the speed of light. Today, the metre is defined as the distance light travels in a vacuum in 1/299,792,458 of a second.
Q15. The need to measure distance arises because:
We need to measure distance for many reasons. We measure distances between places to know how far they are, we measure the size of objects to know their dimensions and we measure distances to plan and build things like buildings, roads and bridges. Accurate measurement is essential in science, construction and daily life.
Q16. Standard units of measurement are needed because:
Standard units of measurement are needed to ensure uniformity and consistency in measurements around the world. Without standard units, different people would use different units, making it difficult to communicate and compare measurements. For example, using the metre as a standard avoids confusion between inches, feet and yards.
Q17. Before the standard system of units, people used:
Before standard units were developed, people used body parts like the foot, handspan and cubit to measure length. However, these were not accurate because different people have different sizes of body parts. This led to confusion and the need for a standard system of measurement.
Q18. The handspan is the distance between the:
A handspan is the distance between the tip of the thumb and the tip of the little finger when the hand is fully stretched. It was used as a unit of measurement in ancient times. However, since handspans vary from person to person, it was not a reliable unit.
Q19. The cubit is the distance between the:
A cubit is the distance from the elbow to the tip of the middle finger. It was used as a unit of measurement in ancient Egypt and other civilizations. However, like the handspan, it varied from person to person and was not accurate.
Q20. The foot was used as a unit of measurement in the past. It was based on the length of:
The foot was a unit of measurement based on the length of a person’s foot. It was used in many ancient cultures. However, since feet vary in size, it was not a standard unit and caused confusion. Today, the foot is still used in some countries but is defined as exactly 0.3048 metres.
Q21. The unit of length used for measuring long distances is the:
The kilometre (km) is the unit of length used for measuring long distances like the distance between cities, countries or roads. One kilometre is equal to 1,000 metres. The metre is used for shorter distances, and centimetres and millimetres are used for very short distances.
Q22. The unit of length used for measuring the length of a pencil is the:
The centimetre (cm) is a convenient unit for measuring the length of objects like a pencil, a book or a table. One centimetre is one-hundredth of a metre. A standard pencil is about 15 to 18 centimetres long.
Q23. The unit of length used for measuring the thickness of a sheet of paper is the:
The millimetre (mm) is the unit used for measuring very small lengths like the thickness of a sheet of paper or a coin. One millimetre is one-thousandth of a metre. It is a very precise unit used in science and engineering.
Q24. The motion of a swing is an example of:
The motion of a swing is periodic because it moves back and forth at regular intervals. The time taken for one complete swing is always the same. This periodic motion is used to make clocks and pendulums.
Q25. The motion of a spinning top is an example of:
A spinning top shows rotational motion because it spins around its own axis. Rotational motion is a type of circular motion where the object rotates around a fixed axis. Other examples include the rotation of the Earth and the wheels of a car.
Q26. The motion of a ball thrown in the air and then falling down is an example of:
A ball thrown in the air follows a curved path, which is called curvilinear motion. Curvilinear motion is the motion of an object along a curved path. This is different from linear motion, which is along a straight line.
Q27. The motion of a train on a railway track is an example of:
A train moving on a straight railway track shows linear motion because it moves along a straight line. Linear motion is the simplest type of motion. If the train moves on a curved track, it would be curvilinear motion.
Q28. The motion of a clock pendulum is periodic because:
The motion of a clock pendulum is periodic because it repeats its back-and-forth swing at regular intervals. This regularity is what makes it useful for measuring time. The time interval between two consecutive swings is always the same.
Q29. The SI unit of length is defined using:
Today, the SI unit of length (metre) is defined as the distance light travels in a vacuum in 1/299,792,458 of a second. This definition is extremely precise and does not change with location. It is based on the speed of light, which is a constant in physics.
Q30. The process of comparing an unknown quantity with a known fixed quantity is called:
Measurement is the process of comparing an unknown quantity with a known fixed quantity called a standard unit. For example, measuring the length of a table by comparing it with a metre scale. The result of measurement is always a number followed by a unit.
Q31. The use of standard units is important because:
Standard units are important because they help us measure accurately, make it easy to communicate measurements and allow us to compare measurements. For example, if everyone uses the metre, we can easily compare the lengths of different objects without confusion.
Q32. Which of the following is a unit of length?
The metre is the SI unit of length. Kilogram is the unit of mass, second is the unit of time, and Kelvin is the unit of temperature. It is important to know the correct units for different physical quantities.
Q33. Which of the following is NOT a unit of length?
Kilogram is a unit of mass, not length. Kilometre, centimetre and millimetre are all units of length. The metre is the base unit of length in the SI system.
Q34. The measurement of length is important in:
Measurement of length is important in many areas, including science and technology, daily life and trade, engineering and construction. We measure length to buy cloth, build houses, make roads and conduct scientific experiments.
Q35. The motion that repeats itself at regular intervals of time is called:
Periodic motion is the motion that repeats itself after a fixed interval of time. Examples include the swinging of a pendulum, the rotation of the Earth and the vibration of a guitar string. Periodic motion is used in clocks to measure time.
Q36. The standard unit of length is not changed over time because:
The standard unit of length is not changed over time because it ensures consistency in measurements. If the standard unit were to change, all previous measurements would become meaningless. The metre is defined based on a constant of nature (the speed of light), so it never changes.
Q37. An object is said to be in motion when its position changes with respect to:
An object is said to be in motion when its position changes with respect to a reference point. For example, when a car moves, its position changes with respect to the road or a tree. Without a reference point, we cannot say whether an object is in motion or at rest.
Q38. The movement of a person walking in a straight line is an example of:
A person walking in a straight line is an example of linear motion because the person moves along a straight path. Linear motion is the most common type of motion. If the person walks in a curved path, it would be curvilinear motion.
Q39. The movement of a child on a merry-go-round is an example of:
A child on a merry-go-round moves in a circle around the centre of the merry-go-round. This is an example of circular motion. In circular motion, the distance from the centre remains constant.
Q40. The to and fro motion of a swing is an example of:
The to and fro motion of a swing is both linear (along a straight line) and periodic (repeating at regular intervals). The swing moves back and forth in a straight line-like arc, and this motion repeats regularly. This is why a pendulum is used in clocks.
Q41. The distance between two points can be measured using a:
Distance can be measured using various instruments like a measuring tape, metre scale or ruler. The choice of instrument depends on the length to be measured and the precision required. For example, a measuring tape is used for long lengths, while a ruler is used for short lengths.
Q42. The motion of the Earth around the Sun is an example of:
The Earth’s motion around the Sun is both circular (it moves in an elliptical orbit that is nearly circular) and periodic (it repeats every year). This motion is called revolution. This periodic motion gives us the concept of a year.
Q43. The SI system is also called the:
The SI system is also called the metric system. It is based on the metre, kilogram and second as base units. The metric system is easier to use because it is based on powers of 10, making conversions simple.
Q44. The first standard unit of length was based on:
The first standard metre was based on a platinum-iridium rod kept in Paris. This rod served as the standard for length for many years. Today, the metre is defined based on the speed of light, which is more precise and unchangeable.
Q45. Which of the following is NOT a type of motion?
Linear motion, circular motion and periodic motion are all types of motion. ‘Standard motion’ is not a recognized type of motion. Motion can be classified based on the path (linear, circular, curvilinear) or the pattern (periodic, non-periodic, random).
Q46. A reference point is needed to:
A reference point is needed to describe the position of an object. For example, saying “the book is on the table” uses the table as a reference point. The reference point helps us locate the object and describe its motion.
Q47. The SI system is based on:
The SI system (metric system) is based on powers of 10. This means that converting between units is very simple. For example, 1 kilometre = 1000 metres, 1 metre = 100 centimetres, 1 centimetre = 10 millimetres. This decimal-based system makes calculations easy.
Q48. If an object does not change its position with respect to a reference point, it is said to be:
An object is said to be at rest if it does not change its position with respect to a reference point over time. For example, a chair in a room is at rest because it does not move from its place. Rest and motion are relative and depend on the choice of reference point.
Q49. The measurement of length is expressed in:
Length is measured in metres and its multiples and submultiples, such as kilometres, centimetres and millimetres. The metre is the base unit of length in the SI system. Kilograms are used for mass, seconds for time, and litres for volume.
Q50. The motion of a rubber ball bouncing on the floor is an example of:
A bouncing rubber ball shows random motion because its path and direction change unpredictably with each bounce. Random motion is motion that is not regular or predictable. Other examples include the motion of dust particles in air and the movement of a football during a game.
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Q51. The length of a curved line cannot be measured accurately with a ruler because:
A straight ruler cannot accurately measure the length of a curved line because it cannot follow the curve. To measure a curved line, we can use a thread or a flexible measuring tape. The thread is placed along the curve and then measured with a ruler.
Q52. The motion of a horse galloping is an example of:
The galloping of a horse is an example of non-periodic motion because it does not repeat at regular intervals. The horse’s speed and gait change constantly. Non-periodic motion is motion that does not have a regular pattern of repetition.
Q53. The SI system was established to:
The SI system was established to provide a uniform system of measurement worldwide. Before the SI system, different countries used different systems, causing confusion in trade, science and engineering. The SI system is now the standard in most countries around the world.
Q54. The motion of a fan blade is an example of:
The motion of a fan blade is rotational because it spins around its fixed axis. Rotational motion is a type of circular motion where the object rotates around an internal axis. Other examples include the spinning of a top and the rotation of the Earth.
Q55. The distance between two cities is usually measured in:
The distance between two cities is usually measured in kilometres because it is a large distance. One kilometre is equal to 1000 metres. Using kilometres makes it easier to express large distances without using very large numbers.
Q56. The length of a room is best measured in:
The length of a room is best measured in metres because it is a convenient unit for moderate lengths. Using metres gives a precise number without being too large or too small. For example, a room might be 4 metres long.
Q57. The SI unit of length was redefined in 1983 based on:
In 1983, the metre was redefined based on the speed of light. This definition is extremely precise and does not change with time or location. The metre is now defined as the distance light travels in a vacuum in 1/299,792,458 of a second.
Q58. An object moving in a circular path has:
An object moving in a circular path shows circular motion. If this motion repeats at regular intervals, it is also periodic motion. For example, the movement of the Earth around the Sun is both circular and periodic.
Q59. The need for standard units of measurement arose because:
The need for standard units arose because non-standard units like handspan and foot were not reliable. Different people had different sizes of body parts, so measurements varied. Standard units ensure accuracy, consistency and easy communication.
Q60. The motion of a car taking a turn on a curved road is an example of:
A car taking a turn on a curved road shows curvilinear motion because it moves along a curved path. Curvilinear motion is the motion of an object along a curved line. This is different from circular motion, which is along a complete circle.