Physics Measurements: Time Measurement

Time Measurement 🕰️

• The primary unit of time is seconds.
• A stopwatch is essential for measuring short time intervals, especially in races.
• Zero error refers to a timing discrepancy, usually 0.5 seconds, which must be subtracted from recorded measurements for accuracy. For example, a race measured at 46 seconds should be adjusted to 45.5 seconds.

Averages

• To calculate an average, sum all measurement values and divide by the total number of measurements.
• In a pendulum experiment, if measured over 20 oscillations across four trials, sum the results and divide by four, then by 20, yielding a final average result (e.g., 0.92 seconds).

Length Measurement 📏

• The main unit of length is meters.
• Long distances are measured with a measuring tape, while standard distances use a meter rule. Micrometers are used for short measurements.
• To find the diameter of a circle on a scaled diagram, subtract the starting point from the ending point and divide by two. For a circle from 2 cm to 28 cm:
  • Diameter = (28 - 2) / 2 = 13 cm.
• For internal diameter, deduct the material's thickness from the external diameter:
  • Internal diameter = External diameter - 2 × Thickness. For instance, if the external diameter is 7.4 cm with a thickness of 0.3 cm:
    • Internal diameter = 7.4 - 2 × 0.3 = 2.8 cm.

Avoiding Inaccuracy

• Parallax Error: This error arises when observing from an incorrect angle. To mitigate it, ensure direct line of sight.
• Zero Error: Occurs when a ruler is not level with the measured object. To avoid this, always align the ruler at the same height as the object being measured.