Unit 1 General physics


Section 1.1 Length and time

  • When making measurements, physicists use different instruments, such as rulers to measure length, measuring cylinders to measure volume and stopwatches to measure time.
    correct alignment
  • A ruler is used to measure length. When using a ruler, be careful to avoid parallax error.
    incorrect alignment


Parallax causes an object to appear shorter or longer depending on how you view it. An object must be viewed at right angles to the scale to measure its length correctly.

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