one end of the spring is fixed on the ceiling, and the other end is connected to a weighing pan with a mass of m=2kg, and an object with a mass of M=1kg is placed inside the pan. The weighing pan remains stationary under the vertical downward force F, F=30N, and when it is suddenly removed, at the moment of disapearing of force F, the pressure of the object on the weighing pan is (g=10m/s²)