Stand on an egg

Actually we will have several people stand on a pair of eggs.
Using levers we transfered the weight of several students to the eggs.

This diagram may help you understand what we did.

The end view shows two eggs placed in soft cups and another two cups are put on top of them.
A long plank (green) was placed on top of the assembly.
The first fulcrum arranged so that the weight of the plank and whatever is on top of it (load) is shared equally by the eggs.

The side view shows the long plank which transfers its weight and the weight on top of it to the eggs.
If the weight (represented by the red arrows) is directly over the second fulcrum no additional load is placed on the eggs.
If the weight is directly over the eggs they will have the entire force working to crush them.
If a weight is put in the middle half of the load is on the eggs and half on the fulcrum.
If it is nearer the fulcrum more of load is on the fulcrum and if it is nearer the eggs they carry more of the load, as indicated by the 10% and 70% arrows.

Now for some of the details that bring this theoretical discussion to reality.

Here an egg is being placed in one of the soft cups.
At the top of the picture is the pair of cups that will be put on top of the eggs.

Because not all eggs are exactly the same size I put a little modeling clay on each of them to spread the force equally.

The plank is now resting on the eggs.

Measure each student's weight before they start.
The first student is stepping onto the plank directly over its fulcrum.
In this case the fulcrum is a hinge to keep the plank from slipping sideways or along its length.
She then slides slowly toward the other end.
It is important to not pick up your feet but to slide them smoothly along the plank.

She made it, not quite all the way but close.
Our first student has about 95% of her weight on the eggs.
We have a helper steady the person who is walking the plank.
It can be a bit wobbly.

The second student is about one quarter of the way along the plank.
So now we have 25% of her weight added to 95% of the first student's weight supported by the eggs

Our second student is at about 85% of the way down the plank and the third has started.

He stepped off then back on.
That's not advisable since that can move the plank sideways which will break the eggs.

But he got away with it.

Then suddenly they dropped.

Yes, it is a bit of a mess.

I don't remember what the total load on the eggs was but it wasn't a record.
We have had more than 400 lbs supported by two eggs.
More than 200 lbs on each egg.

Here is an example of a simple spreadsheet from another test to quickly calculate the result as each student moved to their position.
It includes the weight of the board as well as the students.

One additional pointer.
Eggs can vary considerably in both their size and  the thickness of their shell.

Please let me know if you try this "eggsperiment".

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