Torque & Angular Momentum

τ = r × F; L = r × p.

Concept

Torque & Angular Momentum is a foundational idea in this chapter. The defining relationship is:

$\vec \tau = \vec r \times \vec F$

Conservation of L if external τ = 0.

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 $\vec \tau = \vec r \times \vec F$ and one canonical example.
• See the chapter index for full derivations, traps and exam-grade problems.