erikagudgirl

why not the centre of mass itself???

actually the teacher told us that we are supposed to conserve angular momentum about the point on the surface just below the centre of mass. any idea why?i am confused as to why that specific point

a rod Mis lying on a horizontal frictionless table.a small mass m travelling along the surface comes with speed v and hits the rod elasticallyly at one end perpendicular to the rod thereby coming to rest.we have to calculate the ratio m/M first we conserve linear momentum mv=MV' :v'=(m/M)v eq(i) since collision is elastic,e=1 ;[v'+w(omega)l/2]/v=1 eq(ii) for eq(iii)we need to conserve angular momentum.but about which point will we conserve itand why???