Conservation of energy of falling chimney

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SUMMARY

The discussion focuses on calculating the angular speed of a falling cylindrical chimney using the principle of conservation of energy. The total energy of the system is expressed as the sum of gravitational potential energy (Ep) and rotational kinetic energy (Ek). Participants emphasize the need to equate the initial gravitational potential energy to the sum of rotational kinetic energy and gravitational potential energy at any angle, leading to the isolation of the angular speed (\dot{\theta}) as a function of the angle (\theta) with the vertical.

PREREQUISITES
  • Understanding of conservation of energy principles
  • Familiarity with gravitational potential energy (Ep) and rotational kinetic energy (Ek)
  • Knowledge of moments of inertia
  • Ability to manipulate equations to isolate variables
NEXT STEPS
  • Study the derivation of the rotational kinetic energy formula
  • Learn about moments of inertia for different shapes
  • Explore examples of conservation of energy in rotational motion
  • Practice problems involving angular speed calculations in physics
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and energy conservation, as well as educators seeking to enhance their teaching methods in rotational dynamics.

James01
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Homework Statement



A tall, cylindrical chimney falls over when its base is ruptured. Assuming that the chimney remains intact before it hits the ground, using conservation of energy, calculate its angular speed \dot \theta{} as a function of \theta , the angle which the chimney makes with the vertical.


Homework Equations



Etotal = Ep+Ek

I posted a question yesterday similar to this one. I really do not understand how to tackle this type of question. Any help would be appreciated.
 
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Do they give any more details?

The gravitational potential energy of the chimney is converted into rotational kinetic energy... have you learned about rotational kinetic energy and moments of inertia?
 
I don't remember the formula for the rotational KE... but I gather the question is asking you to set the gravitational PE equal to rotational KE... then just isolate the angular speed term...
 
SpitfireAce said:
I don't remember the formula for the rotational KE... but I gather the question is asking you to set the gravitational PE equal to rotational KE... then just isolate the angular speed term...

Yes, the difference in gravitational potential energy is the rotational kinetic energy.

Calculate the total energy of the system at the beginning E_i which is all gravitational potential energy initally... then at any angle you know by conservation of energy that

E_i = E_r + E_g. (the quantity on the right is rotational kinetic energy plus gravitational potential energy) You can use that to isolate the angular speed...
 
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