Popcorn Science Project

 

This popcorn science project investigates how popcorn works.  Ever wonder how those hard little kernels of corn pop into the soft puffs?  Before starting, if you are not sure how to properly conduct an experiment, you can find out how by following our experiment guide. 

 

First: remember to get permission first if you are not allowed to use the stove without supervision.

Why does it pop?

 

The short story is that a typical un-popped kernel contains a small amount of water in its center.  When heated quickly enough, the water inside the kernel turns into steam.  The steam pushes against the inside of the kernel as it gets hotter and eventually the pressure from the steam overcomes the strength of the kernel and pops it.  The explosion causes the soft tissue inside the kernel to puff outwards, giving a popped kernel its characteristic appearance. 

Well, lets assume for a while that we’re not sure that this is what happens and are merely hypothesizing.  How could we prove our hypothesis?  Why experimentation of course!  The fun part of any popcorn science project.

 

The Control

 

First things first: perform a control.  Get some popcorn and pop some of it, get a rough estimate of how much of it popped and how much did not. 

 

Experimentation

 

Now, what if you warm up the popcorn in a 220 degree oven for a couple of hours and then try to pop it?  Does it still pop?  As you might guess, it does not, but why?  The answer lies with that little bit of water inside each kernel.  When the kernel was heated at the relatively low temperature, the water inside dried up.  So trying to pop these dried out kernels will be fruitless – without the water at the center of the kernels, popping will not be possible.

What other experiments could be run to further convince yourself of your hypothesis?  Here are some ideas: 

·        Soak the kernels for a few hours, and then try to pop them.  Will the extra water help or hinder the kernels in popping?

·        Will any kernels pop if they are heated below the temperature at which water turns to steam?

·        Score the kernels.  If you pierce the hard shell of the kernels, how would that affect their ability to burst from the steam pressure?

·        Does freezing the kernels have an effect?

 

Further Information

 

When you perform these popcorn science project experiments, don’t forget to take a guess (hypothesis) as to the outcome of the experiment before you do one. 

 

Egg Science Project

 

An egg science project is a great way to experience science in a way that you can see and touch.

 

Background

 

Eggs are made of particular kinds of cells found in female animals.  Most animals produce eggs and some lay them outside their bodies - like birds.  For eggs that are laid outside the bodies of the mother, the eggs have a hard coating that protects it from damage.  We are going to assume you are interested in these types of eggs - those commonly attainable as chicken or duck eggs.

 

The contents of an egg include: proteins, fats, vitamins, and carbohydrates.  These materials are meant to be used by a chick (baby animal) that would develop inside the egg - farmers collect eggs from domesticated animals (chickens) before they are fertilized (before a baby animal is started inside the egg) so that we can use what's inside the egg for food.

 

You may get more ideas for an egg science project at the American Egg Board.

To jump to a particular area, pick from: Background, Spun Eggs, Swimming Eggs, Sinking Eggs, The Egg Drop, Hydrodynamics, or From Eggs to Chicks.

 

Spun Eggs

 

Ever wonder how you can tell the difference between a raw egg and one that's been hard boiled?  Try this simple egg science project: you will need two eggs (one raw and one hard-boiled) and a large flat surface area (like a large kitchen table.)  Take the raw egg, set it on it's side and then try to spin it with your fingers. 

 

Notice how you cannot seem to get it to spin more then a few rotations a second.  Now take the hard-boiled egg and try the same spinning maneuver - now with this one, you can really get it to spin fast - in fact, if you spin it faster than about ten revolutions a second, it will actually stand on end as it spins!

Why does the raw egg spin slowly?  The fluid inside the raw egg will slide inside the egg as you try to spin it - so most of the mass of the egg does not attain the rotational velocity you are trying to put into it.  Since most of the mass of the egg is in the fluid, the egg tends to stabilize at a rotational velocity equal to that of the fluid - much slower the you tried to spin it at.

 

A hard-boiled egg, on the other hand, has most of it's mass as a solid and so will attain the same rotational velocity as the spin you give the egg and will spin faster than the raw egg will. 

 

Why does the hard-boiled egg stand on end if you spin it fast enough?  That gets a little technical for this egg science project, but the upshot is that it becomes 'easier' for the egg to spin on end than on it's side, so it trades kinetic energy (it's spin on it's side) for potential energy (standing on end - there is now energy to be regained when it falls back down.) 

 

 

Swimming Eggs, Sinking Eggs

 

This egg science project requires a clear container large enough to hold a few glasses of water, a raw egg and some salt or sugar or both. 

 

When you place an ordinary egg in a vessel of water, does it float or sink?  The answer has to do with density: if the egg is denser than the liquid surrounding it, it will sink and if the liquid is denser than the egg, the egg will float.  What do you think will happen if the density of the egg is equal to that of the liquid?

 

There are many ways to do this experiment, just be sure to follow the correct procedure when doing an experiment so you can repeat it if need be and report on it later.  One way to start is to fill your container with plain tap water and then place an egg at the top of the waterline and let the egg go.  Does it float or sink?  Then try adding salt or sugar to the water - does the egg sink if it was floating (or float up if it was sunk?) 

 

You may want to place a soft cloth at the bottom of your vessel to prevent the egg from cracking if it sinks too quickly during your experimentation.

 

The Egg Drop

 

This egg science project is a bit more advanced than the others, and requires more preparation.  The experiment, in brief,  involves making a container that will hold an egg and prevent the egg from being damaged when that container is dropped from a pre-determined height.

 

If you'd like to try this egg science project it would be a good idea to setup the parameters of your experiment first: what kind of materials do you plan to use, at what height are you going to drop the egg, what kind of surface will the container be dropped onto, and so on.  If you have the mathematical and physics knowledge, you may want to determine the forces involved and make predications about the outcome of the experiment using various modeled containers.

 

This can be an exciting egg science project, but it requires a significant time invest to do it properly - and it may help to do it in a group so that the work can be divided up.

 

There are many ways to solve this problem depending on the height from which the egg container is dropped and onto what surface it is dropped.  The problem gets much more difficult to solve for every foot of height that is added - do you know why that might be?