Calculating drop heights based on known forces

[robwrightham]

I have a fixed object of known mass (12kg) being impacted by an air pistion of known force (), I desperatly need to be able to calculate what height an object would have to be dropped to have the same force imparted to it that a specific known piston would.
what equations do i use and what other data do i require?

 

[haael]

You need to know the time period the force is acting and the distance on which the object decelerates after dropping.

 

[robwrightham]

You need to know the time period the force is acting and the distance on which the object decelerates after dropping.

the time period is easily calculated, but what do you mean by "distance on which the object decelerates after dropping" how do i calculate this?