Lecture on Kinetic Energy

Introduction to Kinetic Energy

• Definition: Kinetic energy is the energy possessed by an object due to its motion.
• Applicability: Applicable to any moving object, from a plane to a particle.

Factors Affecting Kinetic Energy

1. Speed:

   • Faster moving objects have more kinetic energy.
   • Energy is transferred to an object to increase its speed and is stored as kinetic energy.

2. Mass:

   • With equal speeds, an object with more mass has more kinetic energy.
   • Example: A plane vs. a particle at the same speed, the plane has more kinetic energy due to larger mass.

Calculating Kinetic Energy

• Equation:
  • ( E_k = \frac{1}{2}mv^2 )
  • Variables:
    • (E_k): Kinetic energy
    • (m): Mass (kg)
    • (v): Velocity (m/s)

Conversion of Units

• Mass:
  • Convert tons to kilograms (1 ton = 1000 kg)
  • Convert grams to kilograms (1 gram = 0.001 kg)

Example Calculation

• Scenario:

  • Plane: Mass = 20,000 kg, Speed = 5 m/s
  • Particle: Mass = 0.0001 kg, Speed = 4000 m/s

• Steps:

  1. Calculate for Plane:
     • ( E_k = 0.5 \times 20,000 \times 5^2 )
     • Result: 250,000 joules (or 250 kJ)
  2. Calculate for Particle:
     • ( E_k = 0.5 \times 0.0001 \times 4000^2 )
     • Result: 800 joules (or 0.8 kJ)

Conclusion

• Despite high speed, lower mass results in lower kinetic energy.
• Example demonstrates the effect of mass and speed on kinetic energy.