Work, Energy, and Power

Introduction

• Start of the live class on Work, Energy, and Power chapter.
• Understanding work, energy, and power is crucial in physics.

What is Work?

• Work is defined in different ways.
• Difference between work in biology and work in physics.
• In physics, work occurs when an object is displaced.
• Example: Kicking a football causing displacement.

Mathematical Description of Work

• Work = Force × Displacement
• When there is an angle between force and displacement, the formula: Work = F * d * cosθ
  • Where F = Force, d = Displacement, θ = Angle between force and displacement.

Types of Work

Positive Work

• When the angle between force and displacement is less than 90 degrees.
• Example: Pushing a door.

Negative Work

• When the angle between force and displacement is greater than 90 degrees.
• Example: Work done by gravity when a person climbs stairs.

Zero Work

• When the angle between force and displacement is 90 degrees.
• Example: Work by centripetal force in circular motion.

Units of Work

• Basic unit: Joule (J)
• One Joule = 1 Newton × 1 meter
• Other units: Calorie, kilowatt-hour.

Formula and Calculation

• Work done formula: W = F * d
• As a dot product: Work = F • d
• Scalar quantity: Work has no direction.

Other Important Points

• Description of constant force
• Applying constant force is difficult for humans.

End of Class

• Discussion of live and recorded classes.
• Feedback and suggestions from students.
• Schedule of future classes.

Note: Keep revising notes and answer questions in the live class.