Why is it harder to hammer in a nail the deeper it gets?

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Discussion Overview

The discussion revolves around the question of why it becomes more difficult to hammer a nail into wood as it penetrates deeper. Participants explore the underlying physics, including the roles of normal force and friction, and whether these factors change as the nail is driven further into the material.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions whether the normal force acting on the nail remains constant or increases as it penetrates deeper into the wood.
  • Another participant suggests that as the nail goes deeper, the friction between the nail and the wood increases due to more surface area contact.
  • A later reply posits that the normal force is indeed increasing as more of the nail is gripped by the wood, challenging the assumption that the normal force is constant.
  • Participants discuss the relationship between normal force and pressure, noting that the normal force is not simply equal to the weight of the nail but is influenced by the interaction with the wood.

Areas of Agreement / Disagreement

Participants appear to agree that the normal force increases as the nail penetrates deeper, but there is no consensus on the implications of this change or how it relates to friction and pressure.

Contextual Notes

The discussion includes assumptions about the nature of friction and normal force that may not be fully resolved, particularly regarding how these forces interact as the nail is driven deeper into the wood.

Who May Find This Useful

This discussion may be of interest to those studying classical physics, mechanics, or anyone curious about the practical applications of force and friction in everyday tasks like hammering a nail.

mrneuro
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Why is it harder to hammer in a nail the deeper it gets?

Classical physics says

F k or s = μ k or s N

the normal force is constant right? or is the nail's normal force increasing as it enters the piece of wood?

or is it one of those exceptions like why wider tires on snow work better than thinner ones? (b/c of pressure exertion over an area)

could someone please explain this its not making any sense
 
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Think qualitatively for a moment. As the nail gets deeper in the material, what has changed?
 
There's more friction with the wood on the sides of the nail.
 
bcbwilla said:
Think qualitatively for a moment. As the nail gets deeper in the material, what has changed?

the pressure exerted by the wood onto the nail in this case the normal force is increasing?

is that why? was i just overlooking the fact that N is increasing in this case and N ≠ mg
 
The normal force (pushing radially inwards) is indeed increasing as more and more of the nail is gripped by the wood.

Whereas, to a very rough approximation, the area of contact doesn't matter for the frictional force between a body and the surface it's resting on, because the pressure goes down if the area goes up, there's no such effect with the nail, because the normal contact force isn't equal to a fixed weight but arises in response to the wood being strained.
 

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