Science Buddies: "Ask an Expert"

Hi there,
My grade is doing the infamous egg drop project this term. the aim is to create a structure to put your egg in so that when it is dropped from 8 meters high, the egg doesn't break. however my school prefers the more theory side to the project so the actual structure is only 30% of our mark while the rest is on a write-up explaining the physics behind this experiment. after much research i have found it to be recommended to build a pyramid shape structure with extended legs and also attach a parachute above it. However i have struggled at finding much explanation on why this is an effective structure. i would much appreciate it if you could give me a detailed explanation on the physics and reliabillity of this structure and any other possible ideas for the design, please note that we have no limitations on materials except that we must include a parachute. thank you!! here is a link to a brief video on the structure known as 'the straw man.' : https://www.youtube.com/watch?v=nsnyl8llfH4

Hello,

take a look at: http://hyperphysics.phy-astr.gsu.edu/hb ... se.html#c1

Force = mass * dV/dt (d=delta or "change in") The parachute reduces dv/dt by adding air resistance. Look up terms like terminal velocity and drag, also look up "how does a parachute work."

Lower velocity at impact will mean lower dv/dt at impact, so lower impact force. You should be able to calculate how much lower this force is.

For the straw part the video gives good hints. When one of the long straws hits the ground, the force is transmitted to the center pyramid straws and then to the egg, but since the center straws are connected to the outer surface of the egg, the force goes into trying to make the egg rotate (like hitting the edge of a disk to make it spin). As the whole structure rotates, a different long straw hits the ground and the process repeats.

In this case impact dv/dt is smaller because dt is larger.

The net effect: The force is spread out over time as multiple long straws hit the ground one at a time.

Let me know if this helps,

good luck