Chapter 13 — Gravitation
Newtonian gravitation, gravitational potential energy, escape speed, Kepler’s laws, satellite orbits, and Earth’s gravitational field.
§12.8 — Q&A
Twenty frequently asked questions about equilibrium and elasticity.
§12.7 — Worked Problems
Seven complete problems covering equilibrium and elasticity. Each problem highlights a different concept.
§12.6 — Elastic Limit & Breaking
All materials can be stretched, but how far? A limit exists beyond which material doesn’t snap back. This is the elastic limit.
§12.5 — Elastic Moduli
Why is steel stiffer than rubber? Because under the same stress, rubber deforms more. This difference in material property is captured by the elastic…
§12.4 — Stress and Strain
A steel wire under 1000 N tension — does it collapse? No! A thin wire (just its own weight) sags more. Why? Because the tension is distributed over…
§12.3 — Rigid Body Equilibrium
The equilibrium conditions are straightforward: forces must balance and torques must balance. But where these forces act matters!
§12.1 — Equilibrium Conditions
A stationary object is satisfying. But when does an object stay put? When all external forces are balanced.
Chapter 12 — Equilibrium and Elasticity
Static equilibrium of rigid bodies, center of gravity, stress, strain, and elastic moduli — from suspended beams to real materials under load.
§11.7 — Q&A
Detailed answers to common questions about rolling motion, torque, and angular momentum.