A rock was thrown horizontally from 100.0 m high cliff . It strikes the ground 90.0 from the base if the cliff. At what speed was it thrown. And a car weighing 12000 N parked on a 36 degree slope. Find the force tending to cause the car to roll down the hill. Find the acceleration of the car rolling down the hill

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.