A thin rod with mass M = 5.99 kg is bent in a semicircle of radius R = 0.603 m (the figure below). (a) What is its gravitational force (both magnitude and direction) on a particle with mass m = 4.65×10^(-3) kg at P, the center of curvature? (b) What would be the force on the particle if the rod were a complete circle?

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1018 · Answer

wasn't able to attend my lecture on laws of gravitation, so I ask for help. haha. thanks

irishboy123 · Answer

|dw:1442743273315:dw|use symmetry in y axis in the x axis, for an easy derivation go to p138 of this https://books.google.co.uk/books?id=DrTecfmiVnAC&pg=PA138&lpg=PA138&dq=gravitational+attraction+semi+circle+mass&source=bl&ots=GOFVqr1CAa&sig=yx6bzZh2pAPExOkwqFbqZDN9gL0&hl=en&sa=X&ved=0CC8Q6AEwAmoVChMI-LCSvKuFyAIV42vbCh31GgmE#v=onepage&q=gravitational%20attraction%20semi%20circle%20mass&f=false formula is there too.