Measuring Physical Quantities

Measuring and Units of Measurement

• Measuring is the process of determining the size, mass, and/or temperature of a quantity of matter or a period of time using instruments marked in standard units.
• Measuring is necessary for clear communication about any quantity of matter.
• The main physical quantities that can be measured are dimensions, volume, mass, time, and temperature.

Physical Quantities and Their Units

• Dimensions: size of an object in terms of length, width, height, or depth, measured in meters (m).
• Volume: amount of space an object occupies, often measured in liters (l) and milliliters (ml).
• Mass: amount of matter an object contains, measured in kilograms (kg).
• Time: duration of an event, measured in seconds (s).
• Temperature: how hot an object is, measured in Kelvin (K).

Standard Units of Measurement

• The International System of Units (SI) is used to ensure consistent and global measurements.

• SI units are used for comparisons in science, and they are shown in the table below:

  • Length: meter (m)
  • Mass: kilogram (kg)
  • Time: second (s)
  • Temperature: Kelvin (K)

Multiple and Submultiple Units

• Multiple and submultiple units have names, such as:
  • 1 kilometer = 1000 meters (1km = 1000m)
  • 1 centimeter = 1/100 meter (1cm = 1/100m)
  • 1 millimeter = 1/1000 meter (1mm = 1/1000m)

Importance of Measuring Instruments

• Estimating is not reliable, and our senses are not accurate.
• Specifically designed measuring instruments and standard units are necessary to obtain consistent and global information.
• Measuring instruments include meter rules, tape measures, calipers, balances, stopwatches, clocks, and thermometers.