(a) The forces acting on the object sitting at rest on the platform are the force of gravity, FGE,o=−mg, and the normal force due to the platform, Fnp,o. This last force is equal, in...(a) The forces acting on the object sitting at rest on the platform are the force of gravity, FGE,o=−mg, and the normal force due to the platform, Fnp,o. This last force is equal, in magnitude, to the force exerted on the platform by the spring (it has to be, because the platform itself is being pushed down by a force Fno,p=−Fnp,o, and this has to be balanced by the spring force).
