Physics Units and Measurements Quiz

Questions and Answers

A measuring instrument and subjective judgement

A known fixed quantity and a measuring instrument (correct)

Only a known fixed quantity

Only a measuring instrument

It should be universally accepted

It should be well defined

It should be easily perishable (correct)

It should be invariable with time

Type and classification

Magnitude and standard (correct)

Name and symbol

Value and comparison

General Conference on Weight and Measures Signup and view all the answers

Temperature Signup and view all the answers

Quantities that do not depend on other quantities for their measurements. Signup and view all the answers

Force Signup and view all the answers

Ampere Signup and view all the answers

Both fundamental and other derived quantities. Signup and view all the answers

Kelvin Signup and view all the answers

Study Notes

Physics relies on precise measurements of physical quantities for accurate results.
Measurement involves comparing an unknown quantity to a known standard quantity.
Accurate measurement is crucial for technological development.
The accuracy of measurement depends on the method and instrument used.

A unit defines the standard for measuring a physical quantity.
Example: "3 meters" indicates the length, where 3 is the magnitude and meter is the unit.
Requirements for a standard unit:
- Universally accepted and recognized.
- Clearly defined and specific.
- Consistent over time and location.
- Easily reproducible and durable.
- Comparable with similar units.
- Adequate size for everyday measurements.
- Readily obtainable.

Fundamental Quantities:
- Basic quantities that do not depend on other quantities for measurement.
- Seven fundamental quantities:
  - Length (metre, m)
  - Mass (kilogram, kg)
  - Time (second, s)
  - Temperature (kelvin, K)
  - Electric current (ampere, A)
  - Luminous intensity (candela, cd)
  - Amount of substance (mole, mol)
Supplementary Quantities:
- Plane angle (radian, rad)
- Solid angle (steradian, sr)
Derived Quantities:
- Depend on one or more fundamental quantities for their measurement.
- Examples include:
  - Density: kg/m³ (derived from mass and volume)
  - Area: m²
  - Volume: m³
  - Velocity: m/s
  - Acceleration: m/s²
  - Force: newton (N)
  - Pressure: N/m²
  - Speed: m/s
  - Work: joule (J)

Fundamental units are the basis for all measurements and remain constant.
Derived units are formulated from fundamental units and describe related physical concepts.