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How to drop an egg in a box without it breaking?I'm given a box with the dimension of...

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janicetay | Student, Grade 11 | (Level 1) eNoter

Posted March 5, 2012 at 6:09 PM via web

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How to drop an egg in a box without it breaking?

I'm given a box with the dimension of 15x15x15cm and i'm allowed to use only 4 materials to avoid my egg from breaking. The box will then be dropped at the fourth floor of a building.

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thice101 | Student, Undergraduate | (Level 1) eNoter

Posted March 5, 2012 at 8:16 PM (Answer #1)

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It’s really very simple, the clue is to spread all the force during the retardation phase (landing) on the COMPLETE surface of the egg. In this way, the resulting (vector) forces will be zero. In other words: The forces will “become a pressure” instead. And, since the egg may be compared to a pressure vessel (the surface is curved and can thus take really a lot of pressure before breaking) the egg will not break if you put it in strong bottle filled with water before dropping it!

This is the classical solution to the problem. I have never worked it out myself but it should work as long as the bottle itself is strong enough (do a test by dropping the bottle filled with just water before doing the test in front of an audience).

 

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najm1947 | Elementary School Teacher | (Level 1) Valedictorian

Posted March 5, 2012 at 9:03 PM (Answer #2)

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The egg is to be dropped from 4h floor - a lot of distance to travel under gravity so you have to increase the drag of air to reduce the speed. Lower the density of package, higher the drag as compared to gravitational pull, hence lower the final velocity at ground.

The density of the package/box can be reduced by filling the box with some low density material like low density foam. It can also be reduced by using a box of very light card.

The box can be made to drop on a predetermined face if a trailing ribbon is added.

Materials:

1. Low density foam 15x15x15 cm

2. light fabric ribbon 2 meters long

3. Thin card box 15x15x15 cm

4. Duct tape

Method:

split the foam in two pieces of 15x15x7.5 cm each

cut a small depression in the center of one piece of foam so that half of the egg can be inserted in it. Insert the egg with narrow end down. mark the opposite side of the foam for identification.

Similarly cut a small depression on 15x15 face of other piece of foam and cover the egg with this piece of foam with depression on the egg side.

Tape the foam pieces together to make it a 15x15x15 cube.

Insert the foam cube in the box with marked side resting in the bottom of the box (The foam will press to get accommodated in the box). Mark the box bottom.

Tape the box so that it holds during the fall.

Tape one end of the ribbon in the center of the top of the box so that it sticks fast to the box and does not tear aprt from the box.

Drop the box from the fourth floor holding it by the ribbon from the loose end.

The box will fall with a relatively slow speed due to drag of ribbon and low total weight. The impact will be taken by the foam and transferred to the egg shell dome.

A dome shape is stongest from the structural point of view and there is no likelihood of damage to egg. The impact on dome is ensured by the foam all around it.

Hope safe landing, however, test before demonstration is recommended.

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bandmanjoe | Middle School Teacher | (Level 1) Senior Educator

Posted March 6, 2012 at 3:04 AM (Answer #3)

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Well, whatever you do, the point is to realize the forces involved and try to minimize the impact that would normally crush the egg into oblivion.  Poor egg! 

It depends on the materials you have to use.  You want to secure the egg inside the box somehow to keep it from rolling around.  You also want to cushion the egg as much as possible to absorb some of the shock that occurs on collision with the ground.  If you have something to build a parachute with, to slow the rapid descent that occurs as the force of gravity pulls the box to the Earth, that would help as well.

I did this experiment this past summer at a college workshop.  Our design was to take a piece of poster paper, roll it from corner to corner to make a cone shape, with a point extending to a larger circular base.  Inside the cone, we inflated a small balloon and pushed it into the "nose" of the cone.  Next we had a small plastic dispensable drinking cup, which we lined with felt.  Next, we put our egg into the felt-lined cup, and used scotch tape to secure the egg in the cup.  We placed the cup on top of the balloon, then inserted a larger balloon, then closed the flaps of the broader side of the cone, taped it with scotch tape to keep it closed.  Then we constructed a parachute out of a plastic grocery bag, connected with plastic drinking straws and tape.  Ours survived a four story fall several times.

Good luck with your design!

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