If a simple pendulum has significant amplitude (up to a factor of $$1/e$$ of original) only in the period between $$t = 0s$$ to $$t = \tau s$$, then $$\tau$$ may be called the average life of the pendulum. When the spherical bob of the pendulum suffers a retardation (due to viscous drag) proportional to its velocity, with $$b$$ as the constant of proportionality, the average life time of the pendulum is (assuming damping is small) in seconds: