Kinetic Energy Lecture Notes

Definition of Kinetic Energy

• Kinetic Energy: Energy possessed by an object due to its motion.
• Applies to all moving objects, from planes to particles.

Factors Affecting Kinetic Energy

1. Speed:
   • Faster objects have more kinetic energy.
   • Energy is transferred to speed up the object, stored in the kinetic energy store.
2. Mass:
   • Greater mass results in more kinetic energy, assuming speed is constant.
   • Example: A plane versus a particle traveling at the same speed.

Calculating Kinetic Energy

• Equation: (E_k = \frac{1}{2} mv^2)
  • (E_k) = Kinetic Energy
  • (m) = Mass (kilograms)
  • (v) = Velocity/Speed (meters per second)

Unit Conversions

• Mass must be in kilograms:
  • Convert tons to kilograms: 1 ton = 1000 kg.
  • Convert grams to kilograms: 1 gram = 0.001 kg.

Example Calculations

1. Plane:
   • Mass: 20 tons = 20,000 kg
   • Speed: 5 m/s
   • Calculation: (0.5 \times 20,000 \times 5^2 = 250,000) Joules = 250 kJ
2. Particle:
   • Mass: 0.1 grams = 0.0001 kg
   • Speed: 4000 m/s
   • Calculation: (0.5 \times 0.0001 \times 4000^2 = 800) Joules = 0.8 kJ

Key Observations

• Even with higher speed, lower mass results in less kinetic energy.
• Importance of both mass and speed in determining kinetic energy.

These notes summarize the key points from the lecture on kinetic energy, including definitions, factors affecting kinetic energy, how to calculate it, unit conversions, and example problems. Remember that kinetic energy is measured in joules.