The period T of a pendulum is given by:

where L is the length of the pendulum while

is the gravitational acceleration.
In the pendulum of the problem, one complete vibration takes exactly 0.200 s, this means its period is

. Using this data, we can solve the previous formula to find L:
zero.
from newton's first law of motion
Newtons first law of motion is also known as the law of inertia
deceleration or rėtardation i’m pretty sure (it won’t let me say the second word but it’s correct)
pitch is the perceived frequency of a sound wave.