A semicircular wire has a length L and mass M A particle of mass m is placed at the centre of the circle.
Find the gravitational attraction on the particle due to the wire.
In the semicircle, we can consider, a small element dθ
Then, mass of R dθ =(ML)RdθdF=GMRdθmLR2dF1=2dFSince=2GMmLRsinθdθ∴F=∫π20−2GMmLRsinθdθ=2GMmLR[−Cosθ]π20=−2GMmLR(−1)=2GMmLR=2GMmLLπ=2πGMmL2