Which of the following units is used to express the frequency of an oscillation?

The total mechanical energy (sum of kinetic energy and potential energy) of a simple pendulum bob is 0.02 J. The speed of the bob at its equilibrium position is approximately: (Mass of the bob = 20 g)

Savitha, a Class XI student, while conducting an experiment to determine the effective length of a simple pendulum L, notes down the time taken to complete 30 oscillations as 60 s. What is the calculated effective length of the simple pendulum? (Take π2 = 9.8 and g = 9.8 m/s2)