impact speed

I think I once read that 15fps descent is like dropping an object from 4 feet. Is that correct, or can some physics genius calculate what the right height is?

I was experimenting with a new construction technique. To test its strength, I dropped it on the bathroom floor from 4 feet, to simulate impact (at 15fps???). Then I tried 6 feet. Then I threw it hard onto the floor at 50% armstrength. It broke on that last test.

What should I conclude aside from the fact that I need a new bathroom floor tile?

Geof

Actually it works out to a little more than 3.5 feet.

Originally posted by geof
I think I once read that 15fps descent is like dropping an object from 4 feet. Is that correct, or can some physics genius calculate what the right height is?

I was experimenting with a new construction technique. To test its strength, I dropped it on the bathroom floor from 4 feet, to simulate impact (at 15fps???). Then I tried 6 feet. Then I threw it hard onto the floor at 50% armstrength. It broke on that last test.

What should I conclude aside from the that I need a new bathroom floor tile?

Geof

Click to expand...

The drop height, d(feet), is related to the impact velocity, v (fps) by the equation: d = (v^2)/2*G = (v^2)/64. (G = 32 fpsps)

v = 16 fps; d = 4'
v = 32 fps; d = 16'
v = 64 fps; d = 64'
etc.

Your test drop should be on the same surface as you are actually landing on. Grass is more forgiving than ceramic tile.

Bob

Originally posted by geof
I think I once read that 15fps descent is like dropping an object from 4 feet. Is that correct, or can some physics genius calculate what the right height is?
Geof

Click to expand...

It is a simple energy balance. The potential energy at some height (m*g*h) is equivalent to kinetic energy at impact (0.5*m*v**2). Solve for h. I prefer to do so in SI units