It doesn’t take a PHD in Physics to know why foam packaging works

on July 25, 2013

Everyone knows what happens when you drop an egg on the floor.  It goes splat.  Now if you wrap the egg in bubble wrap and foam, you can drop it, the egg won’t break.  From a physics standpoint, there are actually two related models that can explain why the egg won’t break.

First model is kinetic energy.   Every object in motion has kinetic energy.   That energy is related to the mass of the object and the speed.   The heavier the object and or the faster the speed, the more kinetic energy.     What happens when the egg hits the floor?   Well there is another principle that comes into play called conservation of energy.   What that means is that energy does not just disappear, but transforms into other types of energy; heat, vibration, friction and sound.   In the case of the egg dropping, most of the energy gets imparted to the egg, and because the egg is relatively fragile it breaks and  the contents of the egg splattering as result of the transfer of energy from one state to another.

What does foam do?   If an egg is wrapped well enough in foam, most of that kinetic energy gets absorbed by the foam as pocket of air compress creating that cushion.  If there is enough compression, then the egg is preserved.   In this case most of the kinetic energy is transformed into heat.

The second physics model is force using the famous formula force equals mass times acceleration (F=MxA).  In this case acceleration is negative acceleration as when the velocity of the egg goes to zero.  If the time span that the egg decelerates is very small (infinitesimal) then that acceleration number is big and the force is very large.   What does foam do?  Foam changes the acceleration factor by slowing the velocity of the egg down gradually.   We are probably only talking about 1/8 inch, but going from stopping in an infinitesimally small distance to something near 1/8” is a huge difference and reduces the force significantly.  

Packnet uses foam packaging to protect objects from absorbing too much energy or being exposed to too much force during shipment.   There are various types of foams with different levels of cushioning.  The type and density of foam needed depends on the size, weight and delicateness of the object.   Packnet specializes in designing the best foam packaging system to meet your needs, even though we may not have PHD’s in physics.