Physics Lecture: Work and Power

Introduction

• Focus on Work and Power.
• Work formula: Fundamental for understanding energy formulas.

Work

• Formula: ( W = F \times d )
  • ( W ) = Work
  • ( F ) = Force
  • ( d ) = Distance
• Similar to moments formula but focuses on distance in the direction of force.
• Example:
  • 10 Newtons force over 2 meters = 20 Joules.
• Work is a scalar quantity.

Work in Different Scenarios

1. Dropping Object
   • Force: Weight (( mg ))
   • Distance: Height
   • Related to Gravitational Potential Energy (GPE).
2. Accelerating Object
   • Force: ( ma ) (mass ( m ), acceleration ( a ))
   • Use average velocity for acceleration.
   • Kinetic Energy: ( \frac{1}{2} mv^2 ).

Force Components

• Direction of force affects work.
• Example:
  • 10 Newtons at 60 degrees over 10 meters.
  • Use cosine for component in force direction.

Power

• Definition: Rate of work.
• Formula: ( P = \frac{W}{t} )
  • ( P ) = Power
  • ( W ) = Work
  • ( t ) = Time
• Measured in Watts (W).

Example

• Moving object with 10 Newtons over 2 meters in 2 seconds:
  • Work = 20 Joules
  • Power = 10 Watts

Replacing Work with Energy Formulas

• Any energy formula can substitute work.
• Examples include:
  • Specific heat capacity (( mc\Delta T )).
  • Gravitational potential energy (( mgh )).
  • Kinetic energy (( \frac{1}{2} mv^2 )).

Conclusion

• Importance of the work formula in energy-related calculations.
• Power as a measure of how quickly work is done.