Egg Drop

Assignment:

Design and build an egg capsule within a volume of 35x35x35cm without a parachute that will be dropped from 9-10 m.

Ideas:

Ideally, we wanted to have a design that was lightweight and contained lots of cushioning to break the fall.  We wanted to have something soft that would crumple in order to increase impact time and minimize force on the egg.  Increased impact time would lower the force the egg experienced, hopefully preserving it. Also, we should try to decrease the momentum of the egg by creating something with air resistance and low mass. Because momentum is directly related to mass and velocity, by reducing the mass and creating something with air resistance, we can achieve a low starting momentum, which will reduce the change in momentum (or impulse). This will reduce the force on the egg.

Design:

Our original design features a full gallon plastic bag filled with crumpled newspaper with the egg packed safely within the center of the apparatus. This displays the optimal equilibrium of low weight, high air resistance and cushioning. (For more information, see “How it will work”) Below is a diagram of version 1.

Build:

The final build design was simple. A center gallon plastic bag was filled with crumpled paper and newspaper within which would be the egg surrounded by padded material. On two sides of the center bag were two empty plastic bags. These bags were filled with air and had small openings to allow air to seep out.

Below is a diagram of the final project, and pictures of the actual device. Everything is within 35x35x35 cm.

How it will work:

Our final device will follow our original idea. It is both light and contains huge amount of cushioning. We followed the Impulse theory equation of ∆P = F * ∆t to decrease the force on the egg as much as possible. Because P=mv, by reducing the velocity of the device we reduce the momentum as well. Since momentum and force are directly related, by reducing momentum we reduce force on the egg. Along with reducing force from the momentum side, we also reduce it by increasing contact time. The cushions on either side of the central device along with the newspaper inside, act as a sort of air bag. When the apparatus reaches the ground, the airbag, (no matter which one) will deflate and the newspaper will crumple further. This allows for a greater contact time for the system as a whole. Because F=∆P/∆t By increasing time and decreasing momentum, force should be significantly decreased.

Test:

Unfortunately, our design was unsuccessful.  We did not foresee the possibility of the design turning in mid-air.  When we dropped the egg, the design rotated and landed on it’s side rendering the cushioning airbags useless. Because of this, the contact time was significantly shorter, thus, the force on the egg was significantly larger. While it does not count as success, the egg was not completely destroyed.  However, its general shape, inner and outer membrane were completely intact, a feat that could not be achieved without the device. Still, large cracks in the outer shell and mammillary layer were penetrated. This calls for improvement.

How to improve:

When we dropped the egg, the bags turned towards the heavier mass in the middle.  The bags full of air on the side were not able to cushion the impact of the egg hitting the ground.  In order to mitigate this problem, we need to weight the airbags so that they will hit the ground first.  Also, it could prove beneficial to take out some of the stuffing around the egg.  When we dropped our contraption, the bag the egg was in was completely stuffed with paper.  This caused the design to bounce a little when it impacted the ground.  A bounce decreases contact time and increases the amount the momentum changed.  Taking some of the stuffing out would allow for more give upon impact.  Thus, reducing force on the egg.