Simple pendulum

T = 2 π √ ℓ/g        T in s ; ℓ in m ; g in m.s^-2

Example

The duration of one oscillation is 1.0 s.

Find the length of the pendulum.

1.0 = 2 π √ℓ/9.81

1.0/(2 π) = √ ℓ/9.81

0.159 = √ ℓ/9.,81  

0.025 = ℓ/9.81  

ℓ = 9.81 x 0.025 = 0.25 m