Final answer:
The period of a pendulum is affected by its string length and the acceleration due to gravity, and is largely independent of the pendulum bob's mass and swing amplitude.
Step-by-step explanation:
The period of a pendulum primarily depends on two factors: the length of the string and the acceleration due to gravity (g). When you double the length of a pendulum, the period increases, specifically, it becomes the square root of two times longer, because the period is proportional to the square root of the length. If the length is decreased by 5%, the period will decrease but not by a strict factor of 5% because the relationship is not directly proportional. Furthermore, the mass of the pendulum bob and the amplitude (or maximum displacement) of the swing have virtually no effect on the period, especially if the amplitude is less than about 15 degrees. This characteristic allows pendulum clocks to remain accurate and finely adjusted, even when the amplitude changes slightly over time.
In a hypothetical scenario where a pendulum is transported from Earth to the Moon, the period would change due to the difference in acceleration due to gravity. On the Moon, gravity is weaker, approximately 1.63 m/s² compared to Earth's 9.81 m/s². Consequently, the period would increase, and the ratio of the new period to the old period can be calculated using the square root of the inverse ratio of the two accelerations.