# Comparing force of mass at rest vs falling mass

What equations can be used to compare the force of a resting X mass to the force of a smaller Y mass falling Z distance.

Specifically, how much resting mass would equal the force of 300 pounds being dropped from 10 feet up?

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mfb
Mentor
A force from what, where?
The gravitational force between earth and some other mass depends on the distance between the objects, but on the scale of a building you can neglect this effect.

yes, earth's gravitational force applied to a resting mass and a falling mass. I am quite sure that a falling mass produces considerably more force than a mass at rest.

mfb
Mentor
The gravitational force is the same.

The force applied on a surface can be larger at the time the falling mass hits it, as it gets decelerated rapidly. The force depends on details of the collision process.

I think backing up and restating this might help.

Let us say we are comparing the force of a 2000 kg inelastic sphere at rest on an inelastic floor vs a 200kg but same size inelastic sphere dropped 10 ft at sea level on earth.

mfb
Mentor
Initially the second sphere will have a force of zero because it does not touch the floor, then it will have a large force for a very short time (where "large" and "short" depend on details of the collision process), then (resting on the floor) it will have 1/10 of the force.

That much I understand just fine. I want to know what number "large" is. The collision process is something I have simplified as much as possible. It is a point impact between two solid inelastic bodies. Can I get some actual math in here?

haruspex