Elastic Potential Energy Overview

Overview

This lecture explains elastic potential energy, how it is stored in stretched springs, and how to calculate it using a specific formula.

Elastic Potential Energy Concepts

• Elastic potential energy is the energy stored in objects that can be stretched or compressed, such as springs.
• When we stretch a spring, we apply a force, which scientists refer to as doing work on the spring.
• A stretched or compressed spring returns to its original shape if not stretched beyond its limit.

Extension and Force in Springs

• The extension of a spring is the change in length from its original position and is denoted by lowercase "e".
• The extension is directly proportional to the force applied, producing a straight-line graph through the origin.
• If too much force is applied, the spring exceeds its limit of proportionality and does not return to its original length.

Calculating Elastic Potential Energy

• Elastic potential energy (in joules) is calculated using: Elastic potential energy = 0.5 × spring constant × (extension)^2.
• The spring constant (in newtons per meter) varies depending on the spring.
• Extension must be in meters; convert from centimeters by dividing by 100.

Example Calculation

• For a spring with a 20 cm extension and a spring constant of 100 N/m: Convert 20 cm to 0.2 m.
• Substitute into the formula: 0.5 × 100 × (0.2)^2 = 2 joules.

Key Terms & Definitions

• Elastic Potential Energy — Energy stored in a stretched or compressed object.
• Extension (e) — The increase in length of a spring when a force is applied.
• Spring Constant — A value (N/m) that describes the stiffness of a spring.
• Limit of Proportionality — The point at which extension is no longer proportional to the force applied.

Action Items / Next Steps

• Practice calculating elastic potential energy using the provided equation.
• Ensure extensions are converted to meters before calculations.
• Review related questions in the revision workbook.