Pre-Medical Physics Quiz Exercise-I

Unit Systems and Measurements

• SI, MKS, FPS, and CGS are systems of units; not all based on mass, length, and time.
• FPS (Foot-Pound-Second) is primarily used in the U.S. while SI (International System of Units) is used globally.

Unitless Quantities

• Velocity gradient is unitless, differentiating it from pressure, displacement, and force gradients.

Dimensional Analysis

• Surface tension and coefficient of viscosity share mass and length as fundamental units in their dimensional formulas.

Micron to Nanometre Ratio

• One micron equals 1,000 nanometres (10³), highlighting the scale differences between these units.

Temperature as a Derived Quantity

• Temperature can be derived from the combination of length, mass, and time, positioning it as a complex metric in physics.

Density Conversion

• Wood density is 0.5 gm/cc in CGS; its MKS equivalent is 500 kg/m³, showcasing unit conversion proficiency.

Matching Units of Length

• Distance between Earth and stars: Kilometre
• Interatomic distance in solids: Angstrom
• Size of nucleus: Fermi
• Wavelength of Infrared Laser: Micron

Time Units

• Microsecond, leap year, lunar month, and parallactic second are all units of time; the concept of time is diverse.

Smallest Units of Measurement

• Among millimetre, angstrom, fermi, and metre, the fermi is the smallest, relevant to nuclear dimensions.

Relations and Conversions

• Common physical constants:
  • 1 calorie = 4.18 joules
  • 1 Ångström (Å) = 10⁻¹⁰ metres
  • 1 MeV = 1.6 x 10⁻¹³ joules
  • 1 newton = 10⁵ dynes, emphasizing the variation in units across different measurement systems.