The Egg Drop is a classic science class experiment for middle school or high school students. Students are given an egg to drop from a high point (such as the roof of the school) onto a hard surface (such as the parking lot). They must design a carrier for the egg to house it during the drop. Typical carriers are milk cartons or shoeboxes. The students can modify the carrier by adding wings, parachutes, foam interiors or even marshmallow cushions. The students form hypotheses about which of the egg carriers will effectively protect the egg and then test those hypotheses. The experiment is not just for fun -- although students do enjoy it. It is intended to teach students about the relationships between force and momentum.
Newton's Laws of Motion are the basic principles illustrated in the egg drop experiment. Sir Isaac Newton published his Laws of Motion in 1687 and fundamentally altered scientists' understanding of the world by describing the relationship between force and motion. The first of these laws is referred to as The Law of Inertia. In basic terms, an object that is in motion will stay in motion unless an external force acts upon it, and an object at rest will stay at rest unless an external force acts upon it.
In Newton's Second Law, he discusses the direct relationship between the external forces acting upon an object and the object's change in momentum. The force increases as the time required for the change decreases. If a train is moving along at a steady pace and needs to decelerate, the force experienced by the passengers will be greater as the time for deceleration is shorter.
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The objective of the egg drop experiment is to keep the egg from breaking as it decelerates. It becomes clear from Newton's Laws that in order to minimize the force experienced by the egg at impact, students designing the egg carriers must increase the time over which the egg is brought to rest or decrease the egg's velocity at the time of the crash.
In order to decrease the egg's velocity upon impact, students must design their egg carriers to have increased air resistance. An increased surface area on the carrier, such as a flying disc shape or a parachute, will cause the egg to hit the ground at a lower speed. To increase the time over which the egg comes to rest, students must provide their egg with something to absorb some of the force of impact. A sponge or other cushion in their carrier will keep the egg from stopping instantly when it hits the ground; the egg will continue its motion for a few nanoseconds, decreasing the force. From this experiment, students also learn to form and test hypotheses and write up their observations in an organized way.