Physics Lesson 2: Energy

Inquiry Lab - Outcomes of Work

• An archer's bow becomes capable of performing work on an arrow when drawn.
• Heating coal produces steam, which can turn a turbine and convert mechanical energy into another energy form.
• A compressed spring can do work by expanding.

Understanding Energy and Work

• Work requires energy, specifically available energy, to perform tasks.
• Mechanical energy: the energy possessed by an object due to its motion or position.

Mechanical Energy

• Work occurs when an object can exert influence due to its energy.
• Examples illustrating mechanical energy:
  • Bow doing work on an arrow when released.
  • Steam generated from heated coal doing work on a turbine.
  • Compressed spring expanding to do work.
• Mechanical energy is quantified in joules (J).
• Types of mechanical energy:
  • Potential energy: energy stored based on an object's position.
  • Kinetic energy: energy of motion.
  • Combination of both potential and kinetic energy.

Potential Energy (PE)

• Definition: Energy stored in an object due to its position relative to other objects.
• Potential energy can transform into work when released.
• Examples of potential energy:
  • A drawn bow holds potential energy, exerting work on the arrow upon release.
  • Chemical energy in fuel represents potential energy that powers a car's engine.
• Stored potential energy is based on the relative positions of atoms in molecules, releasable through chemical changes.
• Gravitational potential energy example: A textbook's potential energy is linked to its height above the ground, calculated using the formula:
  ( PE_{grav} = mgh )
  where ( m ) = mass, ( g ) = acceleration due to gravity, ( h ) = height.