I have an object of mass=3.915 kg falling down by (300 mm), how can I find the force?
This is the homework area, so I'll assume it's a homework question. Typically in textbooks you are given a force/time diagram, integrated which gives the impulse, or momentum of which a moving object has.
The force is then the value of that graph at any time, with the maximum typically being at time zero, or when the object initially strikes.
However, how the impulse function looks is quite dependent on the maximum force that gets applied. Does a falling object exert the same force falling onto a pillow as it does a concrete floor?
In real life, dynamic impact problems can be quite difficult to quanitify accurately.
Separate names with a comma.