# Distinguishing between Raw Egg and Hard-Boiled Egg

• andyrk
In summary, the conversation discusses the difference in spinning speed and duration between a hard-boiled egg and a raw egg. It is suggested that this can be explained using concepts such as moment of inertia, angular velocity, and conservation of angular momentum. The conversation also touches on the effects of the liquid inside the raw egg and how it interacts with the shell. The conversation concludes by recommending conducting experiments to observe these effects firsthand.
andyrk

## Homework Statement

Why does a hard-boiled egg spin faster than a raw egg?
Why does a raw egg spin longer than a hard-boiled egg?

Can this be explained using moment of inertia, angular velocity and conservation of angular momentum?

## Homework Equations

Can this be explained using moment of inertia, angular velocity and conservation of angular momentum?

Or can this be explained only on the basis of the liquid inside the raw egg which keeps on rotating and thus makes the raw egg rotate longer and as it opposes/slides against the inside of the shell, it slows down the egg?

## The Attempt at a Solution

It is about the difference between the way gooey stuff responds vs how a rigid body responds - also about the mass distribution inside the egg, and the interaction between rigid and gooey stuff.
You have to break down the process involved in each test ... how do the different parts of the egg respond to attempts to change the motion.

It is also hard to spin a raw egg on it's point, and if you touch a hard-boiled egg that is spinning rapidly on it's side so it stops, but very quickly release it, it will resume spinning.

Note: if you have never seen these effects, you should get some eggs and try it. Careful observation will (should) help with your answers.

andyrk said:
Why does a hard-boiled egg spin faster than a raw egg?
Clearly that is not a general rule. It must assume something constant about the circumstances. Was there any more text to the question?
andyrk said:
Why does a raw egg spin longer than a hard-boiled egg?
For this one, it may be the same presumed constant circumstance, or maybe this is assuming the same initial spin rate. Either way, I do not believe the statement is true.
What does happen is that if you stop the spinning egg and immediately let go again, the raw egg will resume turning.
http://www.planet-science.com/categories/experiments/magic-tricks/2012/03/spinning-eggs.aspx

Admittedly I havn't seen the second one either and I think it refers to the stop-release method.

Didn't get that much. Could you please provide a more detailed explanation? If the moment of inertia of of the raw egg increases, how does it effect the velocity with which it rotates?

Um, no, the idea is that you do the work.
But it is not entirely about the moment of inertia of the whole egg - but about the different parts, where they are, and how they are connected together.

## 1. What is the difference between a raw egg and a hard-boiled egg?

Raw eggs have a runny yolk and a liquid white, while hard-boiled eggs have a solid yolk and a solid white.

## 2. How can I tell if an egg is raw or hard-boiled?

If you gently spin a raw egg, it will wobble and not spin smoothly. A hard-boiled egg will spin smoothly and easily.

## 3. Why is it important to know the difference between a raw egg and a hard-boiled egg?

It is important to know the difference because raw eggs can contain bacteria such as salmonella, while hard-boiled eggs are safe to consume.

## 4. Can I use the same cooking method for both raw and hard-boiled eggs?

No, raw and hard-boiled eggs require different cooking methods. Raw eggs can be cracked and used in recipes such as scrambled eggs, while hard-boiled eggs need to be cooked in boiling water for a certain amount of time.

## 5. How long does it take to hard-boil an egg?

The cooking time for a hard-boiled egg varies depending on the size of the egg and how well-done you want the yolk. On average, it takes about 10-12 minutes for a medium-sized egg to become hard-boiled.

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