Table of Contents
Egg Drop Experiment Science: Impulse and Cushioning
The egg drop experiment science school versions skip: one equation predicts which design survives, and you can test it with a tape measure and a dozen eggs.
Here is the one line of egg drop experiment science that almost every classroom version leaves out. The force on the egg, measured in units of the egg’s own weight, equals the drop height divided by the distance the egg takes to stop. Drop from two metres and stop in two centimetres and the egg feels about 100 times its weight. Stop in twenty centimetres and it feels ten.
That ratio is the whole design problem, and it means the winning package is not the strongest one. It is the one that crushes the most.
Key Takeaways
- You will drop eggs from a measured height, record what survives, and measure how far each cushion crushed.
- The concept is impulse: the change in momentum is fixed, so the only thing you control is how long the stop takes.
- Best for ages 8 to 15. Younger kids can build and drop; the arithmetic lands around 10.
- The classic mistake is a rigid box. A hard shell transmits the impact instead of absorbing it.
- Raw eggs carry bacteria. Hands and surfaces get washed afterwards, every time.
What You’ll Need
| Item | How much | Where to get it | If you don’t have it |
|---|---|---|---|
| Raw eggs | 12 | Supermarket | Use cheap eggs; you will break several on purpose |
| Tape measure | 1 | Toolbox | A length of string marked with a pen |
| Kitchen scale | 1 | Kitchen | Assume 58 g for a large egg |
| Step ladder | 1 | Garage | A first-floor stairwell landing with an adult holding the eggs |
| Tarp or old shower curtain | 1 | Garage | Four opened bin bags taped together |
| Cotton wool | 1 roll | Pharmacy | Cut-up socks, scrap wool |
| Bubble wrap | 1 m | Any delivery box | Crumpled newspaper, which works nearly as well |
| Drinking straws | 20 | Kitchen drawer | Rolled paper tubes |
| Sponges | 3 | Kitchen | Foam offcuts |
| Masking tape and string | 1 roll each | Stationery drawer | Any tape, any string |
| Phone with slow-motion video | 1 | Skip the timing variation and measure crush distance instead | |
| Notebook | 1 | Anywhere | This one is not optional; the whole point is the record |
Allergen note: raw egg. If anyone in the house has an egg allergy, run this outside, keep them away from the splash zone, and clean up with warm soapy water.
Time: prep 15 min, experiment 45 min, cleanup 15 min Cost: a dozen eggs plus a roll of cotton wool Mess level: do this outside
Do the Experiment
Step 1 — Weigh an egg and measure your height
Write both numbers down. A large egg is around 58 g. Pick a drop height you can reach safely and measure it with the tape from the ground to the egg, not from the ground to your hand. Everything that follows is meaningless without these two numbers.
Step 2 — Find the bare-egg failure height first
Drop an unprotected egg onto your tarp from 20 cm. Then 40, then 60, then 80. Note the height where it first cracks. This is your control, and skipping it is why most egg drops prove nothing. You now know what you are beating.
Step 3 — Build three packages that each test one idea
Package A: 4 cm of loose cotton wool all round. Package B: the egg suspended in the middle of a bag by four rubber bands or string, so it can travel before anything touches. Package C: a rigid shell, like a small plastic tub with the egg wedged inside. Measure and record the cushion thickness on each one before you drop it.
Step 4 — Drop each package three times from the same height
Same height, same surface, released from still hands. Dropped, never thrown. Three trials per design with a fresh egg each time, because one trial of anything tells you nothing. Record survived, cracked or destroyed.
Step 5 — Measure the crush distance
After each drop, look at the cushion. How much thinner is it where it hit? That squashed depth is your stopping distance, and it is the number that predicts everything. For Package B, measure how far the egg moved inside the bag.
Step 6 — Do the arithmetic for each design
For each package, divide your drop height by the crush distance, in the same units. A 2 m drop with a 4 cm crush gives 200/4, so 50. That is roughly how many times its own weight the egg felt. Rank your designs by that number and compare the ranking to what actually survived.
What you should see: a bare egg usually cracks somewhere between 30 and 80 cm onto a tarp over a hard floor, depending on the floor. Package A survives a 1.5 to 2 m drop most of the time. Package B, the suspended one, usually beats it, which surprises people because it looks flimsier. Package C fails, often spectacularly, from a height where the soft packages were fine. The rigid shell survives and the egg inside does not.
What’s Actually Going On
A falling egg arrives with a momentum you cannot negotiate with. Drop it from height h and it hits at roughly the speed given by v equal to the square root of 2gh, which for 2 m is about 6.3 m/s (NASA Glenn, Beginner’s Guide to Aeronautics). A 58 g egg at 6.3 m/s carries about 0.37 kg·m/s of momentum. Stopping means getting that to zero. No cushion changes the amount that has to go.
What a cushion changes is the time. The impulse-momentum theorem says force multiplied by the time it acts equals the change in momentum (The Physics Classroom). Rearranged, the average force is the momentum change divided by the stopping time. Stop the egg in one millisecond against a hard floor and you need roughly 370 N, about 37 kilograms of force on a shell that holds maybe a tenth of that in the wrong direction. Stretch the stop to 20 milliseconds and the same momentum change needs only 18 N. Twenty times longer, twenty times gentler (HyperPhysics).
Time is awkward to measure with a phone, so use distance instead. If the deceleration is roughly steady over a crush distance d, the average force works out to the egg’s weight multiplied by h divided by d. That is the ratio in the opening paragraph, and it is worth sitting with, because it says the drop height and the crush distance are the only two things that matter. Not the cleverness of the design. Not the amount of tape.
This also explains why a rigid box loses. A hard shell has no crush distance of its own, so the egg inside keeps moving at full speed until it hits the inner wall, and then stops in a millimetre. Suspending the egg in the middle of a volume gives it centimetres of travel before anything touches it, which is why Package B tends to win. It is the same reason a car has a crumple zone instead of a steel bumper: the zone is designed to fail slowly, buying the passengers tens of milliseconds (The Physics Classroom on real-world impulse).
One secondary effect is real and worth naming. An eggshell is a thin curved structure that fails in bending, so spreading the contact over a wider patch of shell helps on top of the crush distance. That is two separate ideas, force reduction and load distribution, and good designs use both.
How to Explain It to Your Kid
Ages 5–8: Give the egg a long time to stop
Have them catch a tennis ball twice: once with stiff hands held still, once letting their hands move back with the ball. Ask which one stung. Say that the egg has exactly the same choice. A soft cushion lets the egg slow down over a long squash instead of a short bang, and that is the only trick there is.
Ages 9–12: The word is force, and you get to choose how much
Introduce the ratio directly. Height divided by squash equals how many times heavier the egg feels. Then give them a target: build something that gets the number under 20 from your drop height, and have them calculate the crush distance they need before they build. Kids who do the arithmetic first build better packages, which is a satisfying thing to watch.
Ages 13+: Impulse, and what the slow-motion camera gives you
Work through the full chain: impact speed from the square root of 2gh, momentum as mass times velocity, impulse as force times time equals change in momentum. Then film a drop at 240 frames per second and count the frames from first contact to full stop. Four frames is about 17 milliseconds. Now compute the force directly and compare it with the estimate from crush distance. The two should agree within a factor of two, and arguing about why they do not is better physics than either number alone.
The question to ask: “If we dropped the same package on sand instead of concrete, what happens to the number?” (The sand adds its own crush distance, so the total stopping distance rises and the force falls. It tests whether they understood that d is the total stopping distance, not just the thickness of their cushion.)
Why Teaching This Early Pays Off
The egg drop is everywhere in schools and it usually teaches almost nothing, because it is run as a contest rather than a measurement. Kids build, drop, cheer, and leave with no equation and no number. The version above pre-loads something specific: that in a collision you cannot change the momentum, only the duration, and that a design problem can have a governing ratio you can calculate in advance.
That is also the fix for a well-documented misconception. Clement’s study of introductory mechanics students found persistent, coherent beliefs that force is tied to motion rather than to change in motion (Clement, 1982). An afternoon where the gentle landing and the violent one come from the same drop height, differing only in stopping distance, attacks exactly that confusion.
The National Research Council’s framework for science education lists planning and carrying out investigations and using mathematics and computational thinking among the eight practices school science is supposed to build (NRC, 2012). Three trials per design and one calculation puts you in both. It will not raise a test score by itself, and nobody should claim it does. It does mean that when impulse shows up in a physics class, your kid has already measured it on a driveway.
Related reading if this lands: our guides to the egg drop challenge as an engineering process and to simple machines you can find around the house.
Before You Start: What Parents Should Know
| Best age | 8 to 15. Under 8 the building is fun but the ratio will not stick |
| Supervision | An adult handles anything above shoulder height and holds the ladder. Mark the landing zone and keep everyone outside it |
| Real hazards | Falls, not eggs. Also raw egg bacteria, so wash hands and surfaces with warm soapy water afterwards, and slippery broken egg underfoot |
| Don’t | Don’t drop from a balcony, window or roof edge, ever, and don’t put anything heavier than the egg inside the package. A falling object you cannot see land is a different experiment with a worse ending |
Keep the drop height modest. A step ladder on level ground with an adult on it, or a stairwell landing, gives you all the height this needs. Height is a variable you are measuring, not a stunt.
When It Doesn’t Work
Everything survives, even the bare egg. Your landing surface is doing the cushioning. A tarp over grass adds several centimetres of crush distance before your design contributes anything. Move to a tarp over concrete or paving and raise the height until the bare egg fails.
Everything dies, even the thick cushion. The cushion is bottoming out, which means it is fully compressed before the egg stops. Thicker, or looser. Packed tight, cotton wool and rice both behave like rock.
The egg cracks before you drop it. Taping a package too tightly puts static load on the shell. Wrap loosely and let the egg sit in the middle without pressure.
Results are all over the place. Almost always release technique or orientation. Drop from still hands, never a throw, and note which end hit first. An egg is much stronger end-on than side-on, and that alone can swamp your design differences.
Someone added a parachute. It works, but it changes impact speed, not stopping time. That is a different variable, so make it a separate design and say so in the notebook rather than mixing it in.
Take It Further With Egg Drop Experiment Science
Find the failure height. Fix one design and drop it from 1.0, 1.5, 2.0, 2.5 and 3.0 m, three eggs at each height. Plot survival rate against height. You get a curve with a transition region rather than a clean cliff, which is itself the lesson: real failure thresholds are fuzzy.
Test the ratio directly. Hold the height fixed and build four packages with 1, 2, 4 and 8 cm of the same cushion. Predict the force ratio for each before dropping. Then drop them. If the 8 cm version survives and the 2 cm version does not, you have found your threshold force, and you can state it in units of egg weights.
Time the collision. Film at the highest frame rate your phone offers. Count frames from contact to rest, convert to seconds, and compute the force from impulse. Compare it to the crush-distance estimate. Write down why they differ.
What to Watch For Over the Next 3 Months
- Week 4: Your kid mentions crumple zones, airbags or crash mats in a car conversation and uses the word “time” rather than “strong.”
- Month 2: They apply it somewhere unrelated, like bending their knees when they jump off something, and notice they are doing it on purpose.
- Month 3: They ask a question the experiment did not answer, such as what happens to the ratio if the egg is heavier. Encourage it. The answer is that the force scales with weight too, so the ratio is the same, and working that out is a genuinely good afternoon.
Frequently Asked Questions
How high should we drop from?
High enough that a bare egg reliably breaks, which on a tarp over concrete is usually 60 to 80 cm, and then a standard test height of 1.5 to 2 m for the packages. Measure it rather than guessing, because the height is half of your calculation.
Can we use a hard-boiled egg to avoid the mess?
You can, and the results will be different. A boiled egg’s contents are solid and share the load with the shell, so it survives drops that destroy a raw one. Use raw eggs for the real test and keep a boiled one as a comparison if you want a second measurement.
Why does the suspended egg beat the thick cushion?
Because stopping distance is what counts, and suspension gives the egg several centimetres of free travel before anything touches it, then slows it over the stretch of the bands. A cushion only gives you the depth it can compress.
Is a parachute cheating?
No, but it answers a different question. A parachute lowers the impact speed, which lowers the momentum you have to absorb. Cushioning lengthens the stop. Both work, and keeping them in separate trials is what makes the result interpretable.
My kid just wants to build the biggest thing possible. Is that bad?
It is a reasonable starting instinct and it usually works, which is the problem. Ask for a prediction and a number before the drop. Once they have calculated that a 10 cm crush beats a 2 cm crush by a factor of five, the bulk stops being the point and the design gets sharper.
About the author
Ricky Flores is the founder of HiWave Makers and an electrical engineer with 15+ years of experience building consumer technology at Apple, Samsung, and Texas Instruments. He writes about how kids learn to build, think, and create in a tech-saturated world. Read more at hiwavemakers.com.
Sources
- The Physics Classroom. “Momentum and Impulse Connection.” https://www.physicsclassroom.com/class/momentum/Lesson-1/Momentum-and-Impulse-Connection
- The Physics Classroom. “Real-World Applications” (impulse and collision time). https://www.physicsclassroom.com/class/momentum/Lesson-1/Real-World-Applications
- Nave, R. “Impulse of Force.” HyperPhysics, Georgia State University. http://hyperphysics.phy-astr.gsu.edu/hbase/impulse.html
- NASA Glenn Research Center. “Free Fall without Air Resistance.” Beginner’s Guide to Aeronautics. https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/free-fall-without-air-resistance/
- Clement, J. (1982). “Students’ preconceptions in introductory mechanics.” American Journal of Physics, 50(1), 66–71. https://doi.org/10.1119/1.12989
- National Research Council. (2012). A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. National Academies Press. https://doi.org/10.17226/13165
