(a) The forces acting on the object sitting at rest on the platform are the force of gravity, \(F^G_{E,o} = −mg\), and the normal force due to the platform, \(F^n_{p,o}\). This last force is equal, in...(a) The forces acting on the object sitting at rest on the platform are the force of gravity, \(F^G_{E,o} = −mg\), and the normal force due to the platform, \(F^n_{p,o}\). 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 \(F^n_{o,p} = −F^n_{p,o}\), and this has to be balanced by the spring force).
