Work, Energy and Power

Content

Work: W = F·d·cos(θ), joules (J)
Kinetic Energy: KE = ½mv², always positive
Potential Energy: PE = mgh (gravitational), PE = ½kx² (elastic)
Mechanical Energy: E = KE + PE, conserved in isolated systems
Power: P = W/t or P = F·v, watts (W)
Work-Energy Theorem: W_net = ΔKE
Conservation: E_initial = E_final (no friction)
Efficiency: η = (Useful output / Total input) × 100%
Key Units: 1 J = 1 N·m, 1 W = 1 J/s, 1 kWh = 3.6 × 10⁶ J