Karl M. answered 08/15/22
Experienced, Highly Rated Undergraduate Math and Physics Tutor
The period, T, of a pendulum is given by
T = 2pi √[L / g];
where L is the length of the pendulum and g is the acceleration of the gravitational field the pendulum is in. Solving for L, we obtain
L = (T^2)(g) / (4pi^2)
On earth, take g ≈ 9.8 m/s^2. For a period of 5 seconds, we would need a length of about 6 meters. On the moon, take g ≈ 1.6 m/s^2. For a period of 5 seconds, we would need a length of about 1 meter.