Egg and Sheet Collision

Question:

TO WHOM IT MAY CONCERN:
I HAVE COME ACROSS A VERY PUZZLING PROBLEM IN ONE OF MY PHYSICS BOOKS. IT STATES THAT IF YOU THROW AN EGG AT A SHEET, NO MATTER HOW HARD IT IS THROWN, IT WILL NOT BREAK. IT STATES THAT THIS IS BECAUSE OF NEWTON'S SECOND LAW. I UNDERSTAND THAT THE SHEET MAY CARRY SOME OF THE MOMENTUM OF THE EGG AND MOVE WITH IT FOR A SHORT WHILE UNTIL IT COMES TO A STOP BUT I AM NOT EXACTLY SURE JUST HOW ALL OF THE ASPECTS OF NEWTONS SECOND LAW APPLY TO THIS SITUATION. IF YOU HAVE ANY INSIGHT ON THIS PROBLEM I WOULD APPRECIATE A RESPONSE BACK.
THANK YOU FOR YOUR TIME,

Answer:

Hi Angela,

Here is the deal. Newton's second law says that the force on an object is equal to its mass times its acceleration. Now picture an egg striking a sheet stretched tightly across some kind of frame. At the instant of the first contact the sheet and egg are touching only in a small area since the sheet is flat and the egg is... well, egg shaped. The force then will be only as much on the small area of contact as it takes to deflect the sheet threads a tiny bit. If this is less than the force required, distributed over the area of contact, to break the egg shell. The net effect in this first instant of contact then will be a deflection of the sheet threads and a negative acceleration on the egg caused by the reaction (Newton's third law) of the force that deflected the threads.

Of course as the egg continues to move into the sheet, the area of contact increases so that the next increment of thread deflection force is spread over more egg shell. And so on and so forth until the egg is brought to a stop. With any reasonable sheet thread material stretched over any reasonable area, at no time during this prolonged collision will the force per unit area on the egg shell exceed its strength. in other words the sheet by deflecting and contacting an increasing area of the egg shell stretches out the time of the collision enough that the acceleration of the egg multiplied by its mass and divided by the contact area remains below the shell fracture pressure.

This information is brought to you by M. Casco Associates, a company dedicated to helping humankind reach the stars through understanding how the universe works. My name is James D. Jones. If I can be of more help, please let me know.

JDJ