Very unlikely this would work - especially without any definition of what you mean by "how hard". Have a look at the wiki page on 'impulse'. How hard something appears to be hit depends not only on the force applied, but how long the impact lasts for so to speak. Think of those that break though the tile towers with a hand strike, it's the very sudden force that breaks the tiles, they would support that same force if applied gradually.
The best (and easiest) way to do this, is using something that is designed for this exact purpose - an acceleration. Force = Mass * Acceleration.