Design a container that lets a raw egg survive a drop. You’ll test cushioning materials with a dummy egg to see how hard each one pushes back, work out how much travel the egg needs, and then estimate the impact force and time before you drop the real egg.
🎯 Goals
- Measure how hard different cushioning materials push back when they are crushed.
- Calculate how much travel a cushion needs to keep the force on the egg below its limit.
- Design and build a container, and predict its impact force and time before you drop it.
- Compare your prediction with the result, calculate your percent error, and explain the gap.
🧰 Materials
🥚Dummy eggs (plastic eggs filled with sand or clay to 58 g), and raw large eggs from your teacher
🧽Cushioning to test: foam sheets, bubble wrap, cotton balls, sponges, straws, paper cups, cardboard tubes, crumpled newspaper
📦Structure: cardboard, paper, index cards, craft sticks, small boxes or cups
🧵Rubber bands, string, and masking tape
📏Meter stick, ruler, and tape measure
📱A phone with slow-motion video, for reading maximum compression and the final drop
⚖️A scale that reads in grams
🪣A tarp or tray for the drop zone, and paper towels
🧮Calculator
📓Physics notebook
📏 Constraints
- The drop height is H = 3.0 m, measured to the bottom of the container. Your teacher may change it, so every calculator asks for H.
- Your container protects one raw large egg. The egg must come out so it can be inspected. It survives if there is no crack and no leak.
- The container fits inside a 15 cm × 15 cm × 15 cm cube and has a mass of 100 g or less without the egg.
- No parachutes, wings, or anything that catches the air. The container must free-fall, so the impact speed is v = √(2gH).
- Test cushioning with a dummy egg only. The real egg gets one drop, the final one.
- Write your prediction (will it survive, and what are the force and time) before you drop the real egg.
- Show every calculation with units: lengths in meters, force in newtons, time in seconds (or milliseconds).
- Safety: nobody stands under the drop. Use a ladder or a balcony only with your teacher’s approval, and clean up any broken egg right away.
1
Make a dummy egg.
Fill a plastic egg with sand or clay until it has a mass of 58 g (0.058 kg), and tape it shut. Check it on the scale. The dummy is for testing, so it can be dropped as many times as you like.
2
Prepare four cushioning samples.
Choose four materials to test, such as foam, bubble wrap layers, a bundle of straws, cotton, a sponge, or crumpled paper. Make each sample at least 4 cm thick and about 10 cm across. Record the thickness.
3
Drop the dummy onto each sample from 0.50 m.
Release it from rest, flat side down. Film from the side with a ruler in view. Step through the video to find the dummy’s lowest point, and read the maximum compression d, which is how far it sank below the original surface. Do three drops per sample and average d.
4
Calculate each material’s stopping force and the travel it would need.
The force is F = mgh ÷ d. At the real drop height H, the travel needed is d = mgH ÷ F. A material is usable if F is no more than the egg’s 40 N limit.
F = m g h ÷ d (from a test drop)
d_needed = m g H ÷ F (travel needed at the real drop height)
The egg’s rough limit is about 40 N of average force, from Activity 5-1-2.
Sample data (use only if you can’t run the tests)
Dummy 0.058 kg, dropped from 0.50 m. Maximum compression: foam
0.012 m, straw bundle
0.010 m, bubble wrap
0.020 m, cotton
0.025 m.
What good data looks like
Soft materials like cotton and bubble wrap give small forces but need a lot of travel. Stiff materials like straw bundles need little travel but can push harder than an egg can take. Look for a material that stays just under 40 N.
📓 Physics Notebook
Which of your materials are usable at all, and which would break the egg? Which would need more travel than fits in the container? Which looks like the best single choice, and why?
5
Warm up with the design formulas.
Read the Deep Dive first if any of these are new. These are the calculations you’ll use for the rest of the project.
Warm-Up
Use g = 9.8 N/kg and the 0.058 kg egg.
6
Sketch two design ideas.
Draw a side view of each container with the egg, the cushion layers, and the available travel in the direction of impact. Check each against the size and mass limits.
7
Build your container.
Cradle the egg so it can’t move sideways and so its weight is spread over a wide area. Put your chosen cushion in the direction of impact. Keep the container within 15 cm × 15 cm × 15 cm and 100 g, with no parts that catch the air.
8
Measure the travel your design provides.
Measure the thickness of crushable cushion between the egg and the container in the direction of impact. A cushion can’t be squashed completely, so use about 75% of its thickness as the available travel d.
9
Predict the result before you drop anything.
Find the force of your weakest cushion layer (from your tests). Then d_needed = mgH ÷ F. If your available travel is at least d_needed and F is under 40 N, the egg should survive, with a predicted force of F and a predicted time of Δt = 2·d_needed ÷ v. Write the prediction in your notebook and show your teacher.
Survives if: F ≤ 40 N and available travel ≥ d_needed
Predicted force: F · Predicted time: Δt = 2·d_needed ÷ v, with v = √(2gH)
In a layered cushion, the weakest layer crushes first, so its force is the one that counts.
📓 Physics Notebook
If your design is predicted to break, change it now: add travel, swap in a different layer, or both. Write down what you changed and why. Your final prediction is the one you’ll be judged against.
10
Drop the dummy egg first.
Put the dummy in the container and drop it from H. Look at the cushion and measure how far it was compressed. This is your last chance to fix a weak spot before the real egg.
11
Drop the real egg.
Put the egg in, close the container, and drop it from H over the tarp. Film the drop in slow motion. Open the container and inspect the egg for cracks or leaks. Record whether it survived.
⚠️ Nobody stands under the drop. Clean up any broken egg right away and wash your hands.
12
Measure what really happened.
Measure the actual crush distance: how far the egg traveled while the cushion compressed, from the video or from the permanent crush in the cushion. Then the actual force is mgH ÷ d and the actual time is 2d ÷ v.
13
Analyze your result.
Whether the egg survived or broke, explain what your numbers show. Did the cushion stay under 40 N? Did it bottom out? Where was your estimate wrong, and why?
Common causes of a gap
A cushion that rebounds, so the permanent crush looks smaller than the real compression. A cushion that bottoms out. An egg that wasn’t centered, so one side took a point load. Friction that held the egg and slowed its travel. A container that was heavier than expected, so it kept pushing on the egg.
📓 Physics Notebook
Write a claim, evidence, and reasoning paragraph that answers the unit’s question: If momentum is always conserved, why does a dropped egg break but a well-packed one doesn’t? Claim: your answer. Evidence: the numbers from your tests and your drop. Reasoning: use momentum, impulse, time, and force.
Question 1
State your predicted force and time, your actual force and time, and your percent errors. Was your prediction too high or too low, and what does that suggest?
Question 2
Did the egg survive? Use your numbers (the cushion’s force against the 40 N limit, and the travel you had against the travel you needed) to explain why or why not.
Question 3
Answer the unit’s question: if momentum is always conserved, why does a dropped egg break but a well-packed one doesn’t?
Question 4
What single change would most improve your design? Use d = mgH ÷ F to say how much, and what it would cost in size or mass.
📤 Turn In
- Your container and the egg, shown after the drop (surviving or failed, with a photo or video)
- Your material test table, with the stopping force of each material
- Your written prediction (survival, force, and time), dated before the drop
- Your actual results with percent errors, and your claim–evidence–reasoning paragraph
- Written answers to the four Conclusion questions