Please help me finding out my physicsproject's topic for class9

Well, look at your physics book. Choose the topic you think is the most interesting. Whether you did it already or not does not matter. What matters is that you learn in your project.

Post what you think you'll be doing!

Thermites

Falling Experiment (Leaning Tower)

Use a crt & magnet to direct an electron beam

Calculate speed of light using reflected light and high speed clock

Use static electricity to light up a fluorescent light bulb

Create a magnet with a coil, nail and battery

I don't know what you mean by physics nine (9th grade?) but there are some easy and challenging ideas that may help. Each one has its own applications to physics.

Good Luck.