Help understanding a physics inertia experiment(Hammer and a heavy block)

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    Block Inertia Physics
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Discussion Overview

The discussion revolves around a physics experiment demonstrating the concept of inertia using a heavy block and an egg. Participants explore the effects of different masses on the force transmitted to the egg when struck by a hammer, examining the implications of inertia and impulse in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes an experiment where a heavy block resting on an egg does not break it when struck, while a lighter block does break the egg under similar conditions.
  • Another participant suggests that a more massive block accelerates less when struck, resulting in less movement during the impact, which may prevent the egg from breaking.
  • A participant expresses confusion about the relationship between force, mass, and the resulting effect on the egg, questioning why a heavier block would not lead to a greater force on the egg.
  • It is noted that the hammer applies an impulsive force rather than a sustained force, which alters the mechanics involved compared to continuous forces.
  • One participant clarifies that the egg's ability to compress before breaking affects how force is transmitted, indicating that the acceleration of the block plays a role in this process.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of force transmission and the role of inertia, with some understanding the concepts better than others. The discussion remains unresolved regarding the precise mechanics at play.

Contextual Notes

There are limitations in the assumptions made about force transmission, the rigidity of the egg, and the nature of impulsive versus sustained forces. These factors are not fully explored or agreed upon.

Who May Find This Useful

This discussion may be of interest to students and educators in physics, particularly those exploring concepts of inertia, force, and impulse in experimental settings.

ShizukaSm
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The experiment is the following:

First part - The demonstrator puts an egg in the table, and places a heavy block resting above the egg, then he applies a force in the heavy block using the hammer, and the egg doesn't break.
Second part - Now he takes the heavy block away, and instead places a lighter wooden block, then applies a force with the hammer again, and breaks the egg.

The explanation to this was "The inertia of the heavy block doesn't allow the egg to break" but I don't really get it. I mean, wouldn't the same force be 'transferred' through the block and act on the egg? The same way if I push one block that touches another, the both will move?

Ps: A similar experiment can be found here, if my explanation was not clear:
http://webapps.lsa.umich.edu/physics/demolab/Content/demo.aspx?id=473
 
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To squeeze the egg you need to accelerate the block. A more massive block will accelerate less, so it will move less in the short time period of the impact. If the force is applied continuously, the it doesn't matter which block you use. But a hammer applies just a short force impulse.
 
Sorry but I still don't get it. What do you mean by it will accelerate less? I mean, I believe you, but I don't get it, take a look at my point of view:

IF I apply a force F in a block (Any block, that is) that force would be transmitted to whatever this block is touching (in this particular case, the egg). So, after applying a force F I would have F + Weight acting on the egg, and thus, the heavier the block the easier it would be to break the egg.

I understand that some part of my reasoning must be wrong, but... where?
 
The hammer doesn't apply a sustained force as AT noted.

It applies what is known as an impulsive force or impulse.

The mechanics of impulse is different from ( and harder than) sustained forces like weight.

http://en.wikipedia.org/wiki/Impulse_(physics )
 
Last edited by a moderator:
Oh, I see, I think I understand a little better now.
Thanks a lot!
 
In order to transmit the same force, the egg would have to be perfectly rigid. But since the egg will compress a little before breaking, the motion (acceleration) of the block matters. The acceleration essentially absorbs the force.
 

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