AP Physics Egg Drop Lab...HELP!!! (1 Viewer)

[Morgan Jolley]

In my AP Physics class, we are doing an experiment where we drop an egg from a window about 20 feet up and have to catch it with some sort of contraption. The contraption must be able to fit in a one cubic foot area (or have its longest dimension be less than a foot long), must weigh less than 50 g, and must actually work.
Any ideas? I've come up with a few ideas of my own, tell me what you think:
1. Cushion (like from a pillow) in a cup or container (but loosely stuffed in so it can compress)
2. Something made from paper clips with cushion to catch the egg, compress, and not break it.
We have to keep the egg from breaking, or else we get a 0. Our grade is calculated as
10,000
(mass of device) x (length of longest side)
and then the highest number someone gets will be a 100, the lowest will be a 70, and all others fit somewhere in between.

 

[Seth_L]

Is the contraption dropped with the egg, or is the egg dropped on the contraption?

 

[Keith Mickunas]

Well initially I thought if you could gather a bunch of spider webs and suspend them across the opening of a box you'd be ok. But I realize that'll be tough to work with. So how about this? Get some nylon stockings, spread them over a box, do the ones on top so they're rather loose, and have successive layers in the box that get tighter. Perhaps put some foam batting in between the layers.

Damn though, this seems like a tough assignment. 50g ain't a lot, is it? That's like a few ounces. Plus hitting a 1 cu ft. target from 20 feet up seems tricky. What if your aim is off?

Here's another idea, a box of jello. If it's deep enough the egg won't break.

Finally, hardboil the egg before the drop, that'll make it less fragile, although it could deform. You could also empty the egg shell, that'll make it real light, although it'll be very hard to drop accurately.

 

[Bill_D]

I remember doing something with styrofoam and rubber bands to successfully protect my egg. I apologize for not remembering the exact details but you want the egg to continue to decelerate when the container comes to a stop. And, you want the container to fall at as slow a rate as possible. Many of my fellow aspiring engineers successfully used parachutes to pull the feat off with minimal protection around the egg but this undoubtedly would not fit into you space limitations.

I do remember everyone using a pillow or similar method should have brought a frying pan to the competition. If you could take your head off and drop it 20 feet, hopefully, you would not use a pillow to cushion the fall. An egg is more fragile than your head.

 

[LarryDavenport]

The cushion is not a good idea. If it's to firm the egg will break on contact of break after bouncing off the cushion.

Try filling a one cubic foot box with four inches of down (feathers) and fill the rest with vegetable oil. I think the oil is thin enough so as not to break the shell on impact, but viscous enough so as the egg won't hit the feathers at full speed. If the egg still breaks on the bottom, move up to olive oil or lotion.

(BTW - though I work for Reviews of Modern Physics, I am just the secretary...my degree is in film).

 

[Daren Welsh]

The egg-catcher has to fit in a 1-cubic-foot volume to begin with, but it can expand, right? Build some sort of frame that will hold nylon panyhose in a way so that when the egg drops, it will land in the middle of the square frame. When the egg lands, the nylon will stretch and hopefully absorb the energy of the fall. If you can, it would be even better if you could set it up so the nylon starts out semi-taut, but then is able to slide through the frame holding it. So the egg would land in the middle and the egg would "pull" the nylon down with it for a short distance. This would allow you to have more length of nylon stretching and would give you a longer deceleration period. Of course, you don't want it stretching so far that it hits the ground before stopping

 

[Francois Caron]

Try filling a one cubic foot box with four inches of down (feathers) and fill the rest with vegetable oil.

How about one layer of down, one layer of oil, one layer of water and one layer of jello? As the egg goes through the layers, it may decelerate very smoothly.
That is unless you have bad aim and miss the edge of the box! Omelette anyone?
Instead of using a box, how about using a container with expandable sides? This way, the liquid will be able to move aside as the egg occupies the space inside the container.

 

[Keith Mickunas]

Daren, that's what I was getting at, but with multiple layers, the bottom layers could be tighter, thus increasing the deceleration quicker once it's already been slowed down a bit.

 

[Keith Mickunas]

Instead of using a box, how about using a container with expandable sides?

Hmm, how about a simple frame with saran wrap (plastic wrap or shrink wrap) around it?

 

[dave_brogli]

When I was in this group "destination imagination" in 8th grade. we had that same excact experiment. My team won by using about 80 straws. Mcdonalds brand or whatever. Glue them with super glue or rubber cement.

I cant give you the right specs for what it should look like (I really couldnt begin to explain) but we had actually dropped an egg from 30 feet!! and it didnt break!!! You want to form your straws into a bowl shape but not as deep. Actually more like a catchers mit.

Try it, it should work.

Good Luck Morgan

 

[Dome Vongvises]

For my physics class in high school, we dropped an egg inside a contraption. Somebody used balloons in their contraption and it worked.

But for your situation, Morgan, I'd try a box with air-filled balloons. Nothing cushions like air.

 

[Andrew Testa]

Morgan,

Approach this from the physics, rather than trying to cast a broad net for contraptions that may or may not work. You first priority is to minimize the deceleration of the egg. How do you do that? You can reduce the deceleration by reducing the applied force on the egg:

dF/dt = M x da/dt

if the applied force is lower, the deceleration of the egg is lower, and the instantaneous energy the egg has to absorb is lower.

The amount of work required to stop all eggs is a constant, and Work = Force x Time. so to reduce the force, increase the time spent decelerating. To increase this, you want a device that's as tall as allowed, that is always in contact with the egg, and that imparts a small resistance at first and increasing resistance as time passes and the egg goes farther into the device.

If you look at what is required from the physics, you can narrow your choice of designs to those than will maximize the effects you need.

From here the problem becomes engineering: what materials and what construction will do what the physics dictates? Since I love to see people learn physics, I'd rather you apply the above and give us back some ideas for what you think would accomplish the task. Then I can help you figure out what device to use.

Andy

 

[Morgan Jolley]

Clear some things up...

The egg is accurate in its fall within a 6' square. We don't have to worry about that (teacher uses a tube and he drops it).

The egg is a Grade A Large Shop-Rite regular white egg. Nothing else is accepted.

The egg falls INTO the device I make. In the Honors Physics classes, they dropped a device attached to the egg, but we have to catch it.

Also, we want the device to be as light as possible. The lighter and smaller the object, the higher our grade (so long as it works).

Apparently, a few years ago, some kid came up with the ultimate device (weighed about a gram, not much bigger than the egg, only 3' by 3') and got a 690 score (a good score is about a 140, 200+ is amazing).

 

[LarryDavenport]

I would be afraid that the Egg would bounce of Jello, but I like your idea of having a layer of water on top of the oil. Perhaps you could do:

water

oil

feathers

jello

 

[Kraig Lang]

Believe it or not, my winning solution to this was Vaseline. I dropped an egg from 56' up in high school science class to a towel wrapped in plastric wrap and smeered with about an inch and a half of vaseline.

I believe I could have gone further but it got a little messy and the egg slipped out of my hand while I was cleaning it. The rules in our match were that we only had 1 egg and whatever happened that's all you had.

I'm sure my reasoning for trying this was flawed...I figured that the vaseline had enough mass but was maliable enough to disperse as much energy as possible without any kind of significant re-transference of energy back to the egg. Maybe someone could explain this much better than I could.

I'll admit, I can't quote formulae to explain the science behind it, but I can say that it was extremely successful.

 

[Dan Mc]

Remember the KISS principal...Keep It Simple Stupid
Take a wire hanger, bend it into a circle of 12 inch diameter. Get a nylon stocking of appropriate size, probably a childs size would work best with the size restrictions. Cut a small hole in the seem at the top of the stocking and thread the circular hanger into it creating sort of a funnel shape. Seal the ends of the hanger together.
Do you get to hold the contraption while the egg is dropped? If so, that's it, shouldn't weigh more than a few grams. If not, build some sort of platform for this.
This is just off the top of my head, so I'd test it for practicality first.

 

[Paul__A]

when we did this, a procrastinating friend of mine ran the first test of his contraption right before it was due, and it didnt work. so as a last resort he took his lunch, and used an overcooked cup of noodles (minus some of the water), and the egg didnt break, to the amazement of everyone in class. chicken flavored, btw.

 

[BrettB]

Apparently, a few years ago, some kid came up with the ultimate device (weighed about a gram, not much bigger than the egg, only 3' by 3')

That's one big-ass egg! Let me guess, chicken coop was near a nuclear test range.

 

[Bob Kavanaugh]

I'm hung on the small, one gram perfect answer....

How about a styrofoam cup full of cotton?

OR... I remember in my physics class, we threw eggs as hard as we could into a bed sheet, never got one to break. So, take a bit of fabric and suspend it by some short poles....

 

[Garrett Lundy]

The bad news is that this will require as much lab research as good ideas.

The good news is that you'll be smashing dozens of inexpensive eggs in the pursuit of science!

Have fun and don't perform the experiment near my car.

PS: If you need some styrofoam for your project stop by my place. I just upgraded my computer and have a shitload of the stuff.