The ratio of the number of sparrows visiting a bird feeder to the number of more interesting birds is 2.10. on a morning when alogether 2790 birds visit the feeder, what is the number of sparows?

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.