PE: Spring & Gravity

Spring: ½kx²; Gravity: mgh.

Concept

PE: Spring & Gravity is a foundational idea in this chapter. The defining relationship is:

$U_{\rm spring} = \tfrac{1}{2}kx^2$

Reference of PE is arbitrary; only differences matter.

Worked Application

Apply the formula to a typical problem from your textbook. Identify the knowns, plug into the equation, and check that the units work out. Always sanity-check the magnitude before accepting an answer.

Common Confusions

• Confusing the variables in the formula — re-read the symbol definitions in the chapter.
• Forgetting unit conversions (cm vs m, g vs kg).
• Ignoring sign conventions where direction matters.

Key Takeaways

• Master the formula $U_{\rm spring} = \tfrac{1}{2}kx^2$ and one canonical example.
• See the chapter index for full derivations, traps and exam-grade problems.