Why do wrecking balls amplify damage done?

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SUMMARY

The discussion centers on the mechanics of wrecking balls used for demolishing buildings, highlighting the combination of kinetic energy and gravitational potential energy that amplifies damage. A 1-ton wrecking ball moving at 15 feet per second generates a peak force of approximately 90,000 pounds when it stops within 1 inch, demonstrating the concentrated impact force. The use of wrecking balls is preferred for larger and stronger structures, while smaller buildings can be demolished using direct mechanical action. The effectiveness of wrecking balls is attributed to their ability to deliver substantial force from a height, which is not achievable with standard motors alone.

PREREQUISITES
  • Understanding of kinetic and potential energy principles
  • Basic knowledge of force calculations (mass times acceleration)
  • Familiarity with demolition techniques and equipment
  • Awareness of structural engineering concepts related to building strength
NEXT STEPS
  • Research the physics of pendulum motion and energy transfer
  • Learn about the design and operation of wrecking balls in construction
  • Explore alternative demolition methods, including explosives and hydraulic equipment
  • Study the calculations involved in force and impact analysis in engineering
USEFUL FOR

This discussion is beneficial for civil engineers, demolition contractors, physics students, and anyone interested in the mechanics of building demolition techniques.

tahayassen
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Homework Statement



A wrecking ball is commonly used to destroy old buildings. The energy comes from a motor pulling a large pendulum back, which then allows it to swing against a wall. Why not just use the motor to do the same work on the wall?

2. The attempt at a solution

The kinetic energy AND the gravitational potential energy is used to break the wall with a pendulum whereas a motor will only have kinetic energy.
 
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For small buildings direct mechanical action is used, see,

http://www.youtube.com/watch?v=I9FP7Y2Ig1Y&feature=related

For large and stronger structures use the ball or explosives, see,

http://www.youtube.com/watch?v=SJkdYuzViqo&feature=related

Calculate the peak force generated when a 1 ton ball moving at 15 ft per second stops within 1 inch. If I did it right I get about 90,000 lbs. force concentrated over a relatively small area. It would be difficult to apply such a force many stories up with machines we have.
 
Spinnor said:
For small buildings direct mechanical action is used, see,

http://www.youtube.com/watch?v=I9FP7Y2Ig1Y&feature=related

For large and stronger structures use the ball or explosives, see,

http://www.youtube.com/watch?v=SJkdYuzViqo&feature=related

Calculate the peak force generated when a 1 ton ball moving at 15 ft per second stops within 1 inch. If I did it right I get about 90,000 lbs. force concentrated over a relatively small area. It would be difficult to apply such a force many stories up with machines we have.

I thought force is mass times acceleration - not mass times speed.

edit: Never mind. I get it now. Thanks.
 
Last edited:

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