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Physical quantities and measurement

Written by Dr. Hamza Farooq (Physics)

Class 9 · Physics · 20 questions

Name: ____________________ Date: ____________

Which of these is a base quantity in the SI system?
- A Length
- B Force
- C Area
- D Speed
What is the SI unit of time?
- A Minute
- B Day
- C Second
- D Hour
The least count of a metre rule is:
- A 1 m
- B 1 mm
- C 1 cm
- D 0.1 mm
The least count of a vernier calliper is usually:
- A 1 cm
- B 0.01 cm
- C 0.001 cm
- D 0.1 cm
What is 5 kilometres expressed in metres?
- A 50 m
- B 50000 m
- C 5000 m
- D 500 m
A screw gauge is mainly used to measure:
- A Time
- B The temperature of a body
- C Very small thickness or diameter, such as a wire
- D The mass of a body
The SI unit of mass is the:
- A Newton
- B Kilogram
- C Gram
- D Tonne
The SI prefix 'milli' means:
- A 10³
- B 10⁶
- C 10⁻³
- D 10⁻⁶
A stopwatch is used to measure:
- A Length
- B Time interval
- C Temperature
- D Mass
Which of these is a scalar quantity?
- A Mass
- B Displacement
- C Velocity
- D Force
Which of these is a base quantity?
- A Force
- B Area
- C Electric current
- D Speed
The SI unit of temperature is the:
- A kelvin
- B degree Fahrenheit
- C degree Celsius
- D calorie
The prefix kilo stands for:
- A 10⁶
- B 10⁻³
- C 10³
- D 10²
The prefix nano stands for:
- A 10⁹
- B 10⁻³
- C 10⁻⁶
- D 10⁻⁹
The least count of a screw gauge is found from:
- A Pitch × number of divisions
- B Pitch ÷ number of circular scale divisions
- C Number of divisions ÷ pitch
- D Length of the screw
A vernier calipers has a positive zero error of 0.02 cm. A measured reading of 3.46 cm is corrected to:
- A 3.48 cm
- B 3.44 cm
- C 3.50 cm
- D 3.46 cm
How many significant figures are in 0.00340?
- A 5
- B 6
- C 2
- D 3
Repeating a measurement several times and taking the mean mainly reduces:
- A Random error
- B The least count
- C The unit of the quantity
- D Zero error
A set of readings that are close to each other but far from the true value is:
- A Accurate and precise at the same time
- B Not precise and not accurate
- C Accurate but not precise
- D Precise but not accurate
2500 m written in scientific notation is:
- A 2.5 × 10⁻³ m
- B 0.25 × 10⁴ m
- C 2.5 × 10³ m
- D 25 × 10² m

Answer key

1. A, 2. C, 3. B, 4. B, 5. C, 6. C, 7. B, 8. C, 9. B, 10. A, 11. C, 12. A, 13. C, 14. D, 15. B, 16. B, 17. D, 18. A, 19. D, 20. C

Length is one of the seven base quantities. Force, speed and area are derived from base quantities.
The second is the SI base unit of time.
A metre rule is marked in millimetres, so its least count is 1 mm.
A common vernier calliper reads to 0.01 cm, or 0.1 mm.
Kilo means 1000, so 5 km = 5 x 1000 = 5000 m.
A screw gauge measures small lengths such as the diameter of a thin wire with high precision.
The kilogram is the SI base unit of mass.
Milli stands for one thousandth.
A stopwatch measures time intervals.
Mass has magnitude only.
Electric current is one of the seven base quantities. The others listed are derived.
The kelvin is the SI base unit of temperature.
Kilo means one thousand.
Nano means one thousand millionth.
Least count = pitch ÷ divisions.
A positive zero error is subtracted: 3.46 − 0.02 = 3.44 cm.
Leading zeros are not significant. The digits 3, 4 and the last 0 count, so three.
Random errors vary from reading to reading, so the mean reduces them.
Precision is closeness of readings to each other. Accuracy is closeness to the true value.
The value between 1 and 10 is 2.5, and the decimal moves three places.