Which of the following is always true about the particles that make up matter? A. They can only be found in solid substances. B. They are too small to be seen with only our eyes. C. They are the same size in all substances, D. They are locked into regular arrangements.​

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.