Work Power & Energy

  • Work (कार्य) : Work is said to be done when a force is applied and the object moves in the direction of the force.
  • Work, Power & Energy is a scalar quantity.
  • Formula: Work (W)= Force (F)×Displacement (d)×cos⁡(θ)
    • : angle between force and displacement
  • No work is done when displacement is zero (even if force is applied).
  • In uniform circular motion, work is zero because angle is 90°.
  • Units:
    • SI Unit = Joule (J)
      • 1 Joule = ergs
      • 1 calorie = 4.186 J
    • CGS = erg
  • Positive Work: Force and displacement in same direction.
  • Negative Work: Force and displacement in opposite direction.
  • Zero Work: No displacement or force is perpendicular.
  • Power (शक्ति) : Power is the rate at which work is done or energy is transferred.
  • Formula: Power (P)= Power is given by \( P = \frac{W}{t} \), where W is work and t is time.
    • Bigger unit = Kilowatt (kW), Megawatt (MW)
  • 1 kW = 1000 W
  • 1 HP (horsepower) = 746 W 
  • Energy (ऊर्जा) : Energy is the capacity to do work.
  • Work and energy have the same units.
    • CGS = erg
    • Commercial = kilowatt-hour (kWh)
      • Joules
  • Types of Energy:
    • Kinetic Energy (KE): Due to motion
      KE= 
    • PE=mgh
      • Where:
      • m: mass (kg)
      • v: velocity (m/s)
      • g: gravity (9.8 m/s²)
      • h: height (m)
  • Energy Conversion
    • Chemical → Mechanical = engine
    • Electrical → Heat = heater
    • Mechanical → Electrical = Generator
    • Solar → Electrical = Solar panels
    • Potential → Kinetic = Falling object

Work Power & Energy