Topics
Classical Mechanics
Explanation
Classical mechanics describes the motion of macroscopic objects — from projectiles to spacecraft — using Newton's laws of motion. The three laws form the foundation: objects at rest stay at rest (inertia), force equals mass times acceleration (F = ma), and every action has an equal and opposite reaction. Work-energy theorem connects the net work done on an object to its change in kinetic energy, while conservation of momentum governs collisions. Gravitational potential energy and kinetic energy interconvert in isolated systems, with total mechanical energy remaining constant in the absence of non-conservative forces like friction.
Key Formulas
Real-World Application
Rocket Launch Trajectory
When SpaceX launches a Falcon 9, the first stage engines generate ~7.6 MN of thrust (F) against a 549,054 kg fully-fueled mass (m). Applying F = ma: a ≈ 13.8 m/s² net (after subtracting g = 9.81 m/s²). As fuel burns, mass decreases, so acceleration increases — exactly as Newton's Second Law predicts. At stage separation (~70 km altitude), the rocket has converted enormous chemical energy into kinetic energy (½mv²) and gravitational potential energy (mgh), with total mechanical energy conserved throughout the ascent.