Bob and Sarah build an electromagnet by wrapping a wire around a nail and connecting the wire to both terminals of a battery. When they test the electromagnet, it can pick up six paper clips. Their teacher wants all groups to pick up at least 10 paper clips. What revisions could Bob and Sarah make to increase the number of paper clips their electromagnet picks up

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.