Recently in a perfomace I was in, the stage was designed to have many traps in the floor to allow characters to pop out for a suprise visit. These traps are fun for those who use them, but not so much when they break.
During a scene when many characters are on stage dancing and jumping around, one of the characters landed with just enough force in just the right spot that the trap broke out from under him, dropping a whopping 10 inches before it became jammed, bruising the actors knees.
Luckily there is a happy ending to this story unlike other disaster stories many actors have. (whoever starred in Spiderman the Musical probably has alot) But how could this happen? over the hours and hours of set up and design how could no one see this could happen? well, now they understand exactly why.
about 12 hours after the event, the cast was brought back together into the theater to explain what happened, what went wrong and how they fixed it to ensure the safety of the cast for the rest of the run.
As it turns out, one of the two-by-fours holding up the trap was split in half when the force of the actor was added to it.
Before, when it was first built, the force of weight landing on the trap was designed to be pushed into a platform beneath the trap instead of being pushed directly to the floor.
This probably has something to do with concurrent forces. The trap itself was designed to hold the least amount of weight it had to (the heaviest person in the show) but no one took into account the fact that as soon as someone jumps on it, the combination of gravity, mass, momentum and force all come into play at once. Plus, if a F=ma, and the actors acceleration was larger than walking (because he was jumping) then the forces all being put onto the trap at once caused the 2-by-4 to break.
I think its really bizaar that one person was able to break a two by four directly in half just from jumping on it a little.
I havent had a chance to go down and see exactly what they did to fix the problem. I think they used a variety of springs and such to allow for the energy to become transferred easily.
As soon as i can find out i will do a little investigation and report back
*No actors were harmed in the making of this blog post*