Simple Pendulum Time Period (T = 2π√(L/g))

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T = 2π√(L/g)

What each symbol means

SymbolWhat it stands for
LLength of pendulum (from support to centre of bob) (m)
TTime period (s)
gAcceleration due to gravity (m/s²)

When to use this

Valid for small angular displacements (θ < 15° where sinθ ≈ θ). Independent of mass of bob and amplitude. Seconds pendulum: T = 2s → L ≈ 1m (at g = 9.8 m/s²). Pendulum in accelerating frame: replace g with g_eff. In elevator going up with acceleration a: g_eff = g + a. NCERT Eq. 13.26.