This isn't a homework question, but I figure this is the best place to put it.
I'm still a little fuzzy on all of the "weight at impact" questions. I'll give you three scenarios, feel free to pick one and explain it as best as possible.
Scenario 1:
I build a pasta/balsa wood/toothpick/Lego/glass/whatever bridge and slowly load it by stacking square weights in the center. I find that it holds 75 lbs with little to no deformation. As I add the next 0.5 lb weight, the bridge shatters and falls to the floor.
How do I calculate how high above the bridge I would have to drop a 5 lb square weight to shatter the bridge?
Scenario 2:
Someone knocks a 1.2 lb crescent wrench off of a scaffold platform. It hits a worker wearing a hard hat, 50 feet below. What's a good way to explain how it would feel? (ie, it's the same as a good whack with a 5 lb hammer, or it's the same as balancing a 24 lb weight on your head, etc.)
Scenario 3:
Someone posted this question in another thread: "ANSI Z97.1 has a standard impact test indicating that an 8 lb steel ball dropped from 4 feet has an impact force of approximately 400 lb. How did they calculate this?"
I know technically you need to know the stopping time or stopping distance, but what would that be if you have a glass marble hitting a thick glass plate? There can't be much stopping time, distance or deformation. I know someone can give me an approximate number for any of the above scenarios that means something in the real world.
Please show your calculations.
Thanks!