Physics Concepts and Measurements

Course Outcome 4 Overview

  • Measurement, Motion, and Acceleration
  • Understand the differences in graphs:
    • Position vs. Time (constant velocity vs. constant acceleration)
    • Velocity vs. Time graphs
  • Differentiate between everyday and physics definitions of acceleration.
  • Employ Newton’s Laws to demonstrate falling objects:
    • Objects near Earth's surface fall with the same acceleration (ignores mass).

Key Concepts in Physics

  • Physics: Fundamental natural science; principles apply to all natural phenomena.

Units and Measurements

  • Metric System: Established in France (1795); SI adopted in 1960.
  • Base SI Units:
    • Length: meter (m)
    • Time: second (s)
    • Mass: kilogram (kg)
    • Temperature: kelvin (K)
    • Electric current: ampere (A)
    • Amount of substance: mole (mol)
    • Luminous intensity: candela (cd)
  • Derived Units: Volume (m³), Density, Pressure.

Common Metric Prefixes

  • Tera (T): 101210^{12}
  • Giga (G): 10910^{9}
  • Mega (M): 10610^{6}
  • Kilo (k): 10310^{3}
  • Centi (c): 10−210^{-2}
  • Milli (m): 10−310^{-3}
  • Micro (μ): 10−610^{-6}

Units of Volume

  • Volume: Space occupied by matter; SI unit: cubic meter (m³).
  • Common unit: liter (L) - volume of 10cmimes10cmimes10cm10cm imes 10cm imes 10cm.
  • Milliliter (mL) is 10001000 times smaller than a liter.

Units of Mass

  • Mass: Standard unit - kilogram (kg).
  • Relationship: 1kg=1000g1kg = 1000g; 1g=1cm31g = 1cm³ of water at 4°C.

Units of Energy

  • Energy: Capacity to do work; SI unit - joule (J).
  • Relation to calorie: 1J=0.2390cal1J = 0.2390cal; 1cal=4.184J1cal = 4.184J.

Geocentric and Heliocentric Theories

  • Geocentric: Earth as the center (Ptolemy).
  • Heliocentric: Sun as the center (Copernicus); improved by Kepler, who provided mathematical proofs for planetary motion.

Kepler’s Laws of Planetary Motion

  1. Law of Ellipses: Planetary orbits are elliptical.
  2. Law of Equal Areas: Equal area covered in equal time intervals.
  3. Law of Harmonies: Square of orbital periods proportional to the cube of distances from the sun.

Earth's Motions

  • Rotation: Time to spin on axis (≈23.93 hours - sidereal day).
  • Revolution: Time taken for the sun to return to the same point (≈24 hours - solar day).
  • Inclination: Earth's axis tilted at 23.439°23.439° affects seasons.
  • Solstices: Points of extreme sun's position; Summer Solstice (June 21) and Winter Solstice (December 21).