what is a pendulum and what is extreme position of the pendulum?

Q. The bob of a simple pendulum takes 1 second to go from one extreme position to the mean position. What is the time period of the simple pendulum?

Q. A pendulum is released from one of its extreme positions. What will be its velocity when it passes the mean position and when it reaches the other extreme position?

Q. A simple pendulum is oscillating between extreme positions $P$ and $Q$ about the mean position $O$. Which of the the following statements are true about the motion of pendulum?

Q. The direction of velocity of a pendulum bob at the right extreme position is:

Q. A pendulum is oscillating about its mean position(B) as shown in the following figure. A and C are the extreme positions of the pendulum during its to and fro motion. The displacement of the pendulum from the position B to the position C, or A, is called ______.