Question

how can we make a simple pendulm

Answer 1

If you want to make a pendulum,
1. Take a long cylindrical wood and cut a piece of 40 cm and other one 15cm.
2. Then cut a thread of 35cm and tie it with the upper wooden piece and then hang a Bob of metal foil.
3. Then that wooden piece which is 40cm long stand it on the stand of made up of wood which is flat and gives the grip.

OR
You can get the video from you tube that how to make a simple pendulum.

... Hope it is right and helpful