Measurements and their errors

• What are the fundamental (base) units of measurement in physics?

  Mass, length, time, amount of substance, temperature, electric current
• Why is knowledge of SI units and their prefixes important in physics?

  To ensure consistent and accurate measurements
• Which SI prefix represents $10^9$?


  Giga (G)
• Convert 5.6 kJ to eV.

  $5.6 \times 10^{21} \text{ eV}$
• What is the difference between random and systematic errors?

  Random errors vary unpredictably, while systematic errors are consistent and repeatable
• What does the term "precision" refer to in measurements?

  Consistency of repeated measurements
• How are uncertainties represented in a graph?

  Using error bars
• If a measurement has an absolute uncertainty of 0.2 and a value of 5.0, what is the percentage uncertainty?

  4%
• What is the purpose of estimating physical quantities?

  To provide approximate values for calculations
• Estimate the order of magnitude of the mass of a car.

  $10^3 \text{ kg}$
• Why is dimensional analysis not required in this specification?

  It is not part of the fundamental skills needed for the course
• What is excluded from the fundamental units of measurement in this specification?

  The candela (light intensity)
• What is the significance of significant figures in measurements?

  They indicate the precision of the measurement
• If a measurement has a value of 12.34 with an uncertainty of 0.05, how should it be reported?

  12.34 ± 0.05
• What is the resolution of a measurement?

  The smallest change that can be detected
• How can random errors be reduced in an experiment?

  By taking multiple measurements and averaging
• If two measurements are 5.0 ± 0.1 and 3.0 ± 0.2, what is the combined uncertainty when adding them?

  ± 0.3
• What is the purpose of error bars on a graph?

  To represent the uncertainty in data points
• Why is it important to estimate orders of magnitude in physics?

  To provide a quick check on the reasonableness of calculations
• Estimate the order of magnitude of the height of a typical room.

  $10^1 \text{ m}$
• What is the fundamental unit of electric current?

  Ampere (A)
• What is the difference between precision and accuracy?

  Precision refers to consistency, while accuracy refers to closeness to the true value
• If a measurement has a value of 100.0 with a percentage uncertainty of 2%, what is the absolute uncertainty?

  2.0
• What is the fundamental unit of temperature?

  Kelvin (K)
• Why is it important to understand the nature of measurement errors?

  To improve the reliability and validity of experimental results
• If a measurement has a value of 50.0 with an uncertainty of 1.0, what is the fractional uncertainty?

  0.02
• What is the fundamental unit of amount of substance?

  Mole (mol)
• What is the purpose of combining uncertainties in measurements?

  To determine the overall uncertainty in a calculated result
• If two measurements are 10.0 ± 0.5 and 20.0 ± 1.0, what is the combined uncertainty when multiplying them?

  ± 15.0
• What is the fundamental unit of mass?

  Kilogram (kg)
• Why is it important to use standard form in physics?

  To simplify the representation of very large or very small numbers
• Convert 0.000045 to standard form.

  $4.5 \times 10^{-5}$
• What is the fundamental unit of length?

  Meter (m)
• What is the purpose of using SI prefixes?

  To simplify the representation of very large or very small numbers
• Convert 2.5 GHz to Hz.

  $2.5 \times 10^9 \text{ Hz}$
• What is the fundamental unit of time?

  Second (s)
• Why is it important to understand the limitations of physical measurements?

  To improve the reliability and validity of experimental results
• If a measurement has a value of 15.0 with an uncertainty of 0.5, what is the percentage uncertainty?

  3.33%
• What is the fundamental unit of electric current?

  Ampere (A)
• What is the purpose of using error bars on a graph?

  To represent the uncertainty in data points