Students creating a housing to protect their egg

This is the classic egg drop experiment. Students try to build a structure that will prevent a raw egg from breaking when dropped from a significant height. They should think about creating a design that would reduce the amount of energy transferred from potential to kinetic energy on the egg shell. Some ways to do this would be to decrease the final speed of the egg using air resistance, increasing the time of the collision using some sort of cushion, transferring the energy into something else, or whatever else they can think of!

Each group of students gets the following:

  • 2 balloons
  • 2 small paper cups
  • 4 straws
  • 1 sq ft of cellophane
  • 4 rubberbands
  • 4 popsickle sticks
  • 2 ft of tape
  • 1 egg (not provided)

Subjects Covered

  • Forces
  • Impulse
  • Energy Conservation

Supplies

Provided by requester

  • One egg for each student group
  • Floor covering (Ex: Newspaper, Tarp)

Provided by us

  • Consumed supplies
    • Balloons
    • Small paper cups
    • Straws
    • Cellophane
    • Rubberbands
    • Popsickle sticks
    • Tape
  • Reusable supplies
    • Scissors

 

Physics Behind the Demo

The Egg hitting the ground is a collision between the Earth and the Egg. When collisions occur, two properties of the colliding bodies are changed and/or transferred: their Energy and Momentum. This change and transfer is mediated by one or many forces. If the force is too strong, it can cause the shell of the egg to crack and break.


Momentum Transfer and Impulse (no Calculus)

Starting with the definition of Force a and knowing that acceleration is just the change in velocity over the change in time

$$ \textbf{F}=ma=m\cdot{\frac{\Delta v}{\Delta t}} $$

If we move the $\Large \Delta t $ to the left side of the equation we can see how Force is related to momentum

$$ \textbf{F} \cdot{\Delta t}=m \cdot{\Delta v}$$

This means that the Force multiplied by the change in time, or duration of a collision, is equal to the mass multiplied by the change in velocity. Momentum (p) is defined as the mass multiplied by the velocity so the right side is the change in momentum. This change in momentum is the Impulse (J)

$$ \textbf{J}= \textbf{F} \cdot{\Delta t}=\Delta \textbf{p}$$

a: In this case we are actually talking about the average force, but to keep things simple we will just call it the force.


Momemtum Transfer and Impulse (Calculus)

In Progress