Answer the following question given this paragraph: 

for the period of a simple pendulum. This result is interesting because of its simplicity. The only things that affect the period of a simple pendulum are its length and the acceleration due to gravity. The period is completely independent of other factors, such as mass. As with simple harmonic oscillators, the period T for a pendulum is nearly independent of amplitude, especially if θ is less than about.


Q: The only things that affect the period of a simple pendulum are its length and the acceleration due to gravity. the period is completely independent of other factors, such as this?


A:
mass