What physics project can you suggest for a group of 3 can do?

try GRAVITY.....

Build a motor - all you need is some insulated copper wire (the kind you sand to have an electrical contact; a magnet; a battery; a stand made of metal.

eddy currents are pretty fun.

electricity and magnetism hah

Well Fist thing that come to my mind is Magnetohydrodynamics (MHD)

This is a Cool thing and not many know about this so it would be a Really Really Cool and interesting thing to do
in toking  about bots that Use MHD

Among other things Eddy current, Electromagnetic induction,
Eclectic Fields Could be Coool
Contact me if u need any help
Hope His Helps
Kaushalya Damitha

For Electromagnetic physics a simple project might be to create a couple of series circuits, and a couple of parallel ones.

Have three or four different batteries, and some various resistors.

Take the resistors and build several series circuits.  For each circuit use a Voltmeter to measure the voltage drop.  Record these drops.

Now place them in parallel and again record the potential difference.

Finally discuss the advantages and disadvantages to each and when it would be a good idea to use a series verses parallel circuit.  Also include some research as to how both series circuits and parrellel circuits are used in real life.  See if how they are used matches with your pro and con list.  Explain this...