Physics Quiz: SI Units and Metrics

Metric System and Units

• The metric system has a prefix system to represent large and small quantities:
  • Giga- means 10^9
  • Micro- means 10^-6
  • Nano- means 10^-9
• There are 7 base units in the SI system:
  • meter (m)
  • kilogram (kg)
  • second (s)
  • electric charge (not specified)
  • Kelvin (not specified)
  • mole (not specified)
  • candela (not specified)

Unit Conversion

• Unit conversion is necessary to ensure proper calculations
• Ways to ensure proper unit conversion:
  • Work in the same system of units
  • Use unit analysis
  • Check units before solving an equation
• Example: 1 kg = 2.2 lb means 1 kg is equivalent to 2.2 lb

Unit Analysis

• Unit analysis is a way to check if an equation is dimensionally correct
• It involves checking if the units on both sides of an equation are equal
• Unit analysis cannot tell if an equation is physically correct or numerically correct
• Example: A = pr^2 and A = pd^2/2 can be checked using unit analysis to determine which is correct

Significant Figures

• Significant figures are a way to represent the accuracy of a measurement
• Rules for significant figures:
  • Non-zero digits are always significant
  • Zeros between non-zero digits are always significant
  • Leading zeros are never significant
  • Trailing zeros are only significant if the number contains a decimal point
• Example: 103.07 has 5 significant figures, 124.5 has 4 significant figures, 0.09916 has 5 significant figures, and 5.408 * 10^5 has 5 significant figures

Problem Solving

• Steps in problem solving:
  • Read the problem carefully
  • Check units and significant figures
  • Perform calculations
  • Check if the answer is reasonable
• Importance of unit analysis and significant figures in problem solving
• Example: Calculating the surface area of a can and the volume of water in a pool