Crushing Cars with Just a Mallet/Sledge Hammer

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SUMMARY

This discussion explores the mechanics behind crushing a car's steel frame using a mallet or sledge hammer. The key principle is that while the mass of the hammer is significantly less than that of the car, the acceleration during impact generates a force that can exceed the car's weight, as described by the formula force equals mass times acceleration (f=ma). Additionally, the concept of pressure, defined as force divided by area, explains why a concentrated force from a sledge hammer can cause more damage than a larger, distributed force, such as that from a vehicle rolling over an object.

PREREQUISITES
  • Understanding of Newton's laws of motion, particularly force and acceleration
  • Basic knowledge of pressure calculations (pressure = force / area)
  • Familiarity with the structural integrity of automotive materials
  • Awareness of impact dynamics and energy transfer during collisions
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  • Research the physics of impact forces in materials science
  • Learn about the structural design of automotive safety features
  • Explore experiments demonstrating force and pressure relationships
  • Investigate the effects of concentrated versus distributed loads on materials
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Physics enthusiasts, automotive engineers, safety analysts, and anyone interested in the mechanics of force and material failure.

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Probably a dumb question:
I've been curious after seeing some of these car bashing type events at universities and such, how is it possible to crush the steel frame of a car using only a mallet/sledge hammer? I thought the steel pillars on the roof of a car was supposed to be able to at least withstand the weight of the car. Is a sledge hammer capable of producing more force than the weight of the car?
These cars are crushed with sledge hammers:
http://www.ccboe.org/cacc/misc/misc_06.htm
http://www-personal.engin.umd.umich.edu/~dce/pictures/carsmash.html
These kids look like they've crushed this car with sledge hammers and/or jumping on it:
http://uAlberta.ewb.ca/events/
I wouldn't even have thought it humanly possible to do this much damage:
http://www.washjeff.edu/phideltatheta/carsmash.html
 
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Side said:
I thought the steel pillars on the roof of a car was supposed to be able to at least withstand the weight of the car. Is a sledge hammer capable of producing more force than the weight of the car?
Certainly! Remember that force is equal to acceleration times mass (f=ma). While the weight (mass) of the hammer is much less than the weight of a car, when you have an impact, the acceleration (deceleration) is enormous, resulting in a force hundreds (or even thousands) of times the weight of the hammer.
 
russ_watters said:
Certainly! Remember that force is equal to acceleration times mass (f=ma). While the weight (mass) of the hammer is much less than the weight of a car, when you have an impact, the acceleration (deceleration) is enormous, resulting in a force hundreds (or even thousands) of times the weight of the hammer.

Wouldn't pressure (pressure= Force / area) have something to do w/ why a sledge hammer (force spread over a small surface area) would inflict more damage than a roll over ( force spread over a large surface area)?
 
Yup. That's why it's better to have your foot run over by an Abrams tank than be stomped on by a woman in high-heels.:biggrin:
 
Danger said:
Yup. That's why it's better to have your foot run over by an Abrams tank than be stomped on by a woman in high-heels.:biggrin:

Umm, I'll take the high heels any day over a friggin tank - and surface area be damned! :bugeye: