What is the best egg drop design?

A light design that both slows the fall (a parachute) and lengthens the stopping distance (a crumple zone of straws or padding).

How much force breaks an egg?

Roughly 25 to 40 newtons of sudden force, depending on the egg and where the force is applied.

Why doesn’t a higher drop always break the egg more?

Because of terminal velocity: above a certain height the egg stops speeding up, so it lands at the same speed.

What does F = Δp/Δt mean?

Force equals the change in momentum divided by the time it takes. Longer stopping times mean smaller forces.

Is this a good STEM activity?

Yes. Try it here first, then build the real thing with straws, tape and a plastic bag.

Egg Drop

Parachute, straws, padding, budget. Will your egg survive? Back to the game

How to play

Each height has a budget. Tap the three part buttons to cycle through your choices: a parachute (none, a napkin, a plastic bag or a bed sheet), a straw cage (short to long straws) and padding (cotton wool or bubble wrap). Bigger and better parts cost more. When you're under budget, press Drop it! and watch. After the landing, a graph shows the force the egg felt through the impact, with a dashed line where an egg cracks. Survive with a gentle landing and a little budget to spare for three stars.

The physics: it's the stopping that hurts

An egg doesn't break because it's falling fast. It breaks because it stops fast. To stop, its momentum (mass × speed) has to go to zero, and the force needed is that momentum divided by the time the stop takes: F = Δp / Δt. Land directly on a hard floor and the shell stops in about a millimetre and a fraction of a millisecond, so the force is enormous. Give it 10 cm of crumpling straws and the same stop takes a hundred times longer, with a hundred times less force. That's the same reason cars have crumple zones and you bend your knees when you land a jump.

In the game the cage and padding act as a squashy spring with damping. If they are too short to stop the egg before they're completely flattened, the egg hits the ground through them, and the force spikes. The impact is simulated 20,000 times a second, so the peak in the graph is the real peak.

Parachutes and terminal velocity

A parachute works on the other half of the problem: it reduces the landing speed. Air drag grows with the square of speed, F = ½ρC_dAv², so a falling egg speeds up only until drag balances its weight. That terminal velocity depends on mass and parachute area, not on height. Above a few dozen metres, the egg hits the ground at the same speed whether you dropped it from a clock tower or the 330 m Eiffel Tower. Doubling the parachute's area lowers terminal velocity by about 30 percent. A parachute also needs a little distance to open, which matters for the short drops.

A real-world challenge

The egg drop is a classic school engineering challenge. Real eggs crack at roughly 25 to 40 newtons of force, depending on where the force lands (the ends are stronger than the sides). Good designs combine a modest parachute with a long crumple zone, and keep everything light: every extra gram has to be slowed down too.

More engineering: ../will-it-hold/ and ../build-a-trebuchet/.

Questions people ask

What is the best egg drop design?: A light design that both slows the fall (a parachute) and lengthens the stopping distance (a crumple zone of straws or padding).
How much force breaks an egg?: Roughly 25 to 40 newtons of sudden force, depending on the egg and where the force is applied.
Why doesn’t a higher drop always break the egg more?: Because of terminal velocity: above a certain height the egg stops speeding up, so it lands at the same speed.
What does F = Δp/Δt mean?: Force equals the change in momentum divided by the time it takes. Longer stopping times mean smaller forces.
Is this a good STEM activity?: Yes. Try it here first, then build the real thing with straws, tape and a plastic bag.