Elastic Potential Energy and Springs

Key Concepts

• Elastic Potential Energy: Energy stored in a stretched spring.
• Work: Applying a force to change the length of the spring, referred to as doing work.
• Extension: The amount a spring stretches when a force is applied, symbolized by lowercase 'e'.

Explanation

• Windup Toys and Clocks: Both use energy from a spring.
• When a spring is stretched, energy is added and stored as elastic potential energy.
• Proportionality: Extension is directly proportional to the force applied until a certain limit.
  • If a force is too great, the spring reaches a limit of proportionality and won't return to its original length.

Calculating Elastic Potential Energy

• Formula: Elastic Potential Energy (in Joules) = 0.5 × Spring Constant × Extension²
  • Spring Constant: Depends on the spring, measured in Newtons per meter (N/m).
  • Extension: Must be in meters (convert cm to m by dividing by 100).

Example Calculation

• Given:
  • Extension: 20 cm
  • Spring Constant: 100 N/m
• Steps:
  1. Convert extension to meters: 20 cm = 0.2 m
  2. Use formula: 0.5 × 100 N/m × (0.2 m)² = 2 Joules
• Result: Elastic potential energy stored is 2 Joules.

Additional Resources

• Refer to the revision workbook for more practice questions on elastic potential energy.

By understanding these concepts, you should now be able to describe and calculate elastic potential energy in stretched springs.