Spinning rod dropping on a pivot

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SUMMARY

The discussion focuses on the dynamics of a long, thin rod of mass M and length L that pivots at its lower end when pushed slightly. The key equations involve conservation of energy, specifically the relationship between potential energy and rotational kinetic energy. The participants emphasize that only rotational kinetic energy is relevant during the fall, and the potential energy of the center of mass contributes to the system's energy transformation. The final goal is to determine both the angular velocity and the speed of the tip of the rod upon impact with the table.

PREREQUISITES
  • Understanding of rotational dynamics and angular momentum
  • Familiarity with conservation of energy principles
  • Knowledge of moment of inertia calculations for a rod
  • Basic physics of motion and forces
NEXT STEPS
  • Study the moment of inertia for different shapes, particularly a thin rod
  • Learn about the conservation of mechanical energy in rotational systems
  • Explore the equations of motion for rigid bodies in rotational dynamics
  • Investigate the relationship between angular velocity and linear velocity at the tip of a rotating object
USEFUL FOR

Physics students, educators, and anyone interested in understanding the mechanics of rotating bodies and energy conservation principles in dynamics.

mjolnir80
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Homework Statement


a long, thin rod of mass M and length L is standing stright up on a table. its lower end rotates on a frictionless pivot. a very slight push causes the rod to fall over. as it hits the table, what are (a) the angular velocity and (b) the speed of the tip of the rod?


Homework Equations





The Attempt at a Solution


could we set up a conservation of energy equation for this?
1/2I(for spinning of rod)\omega^2 + mgh = 1/2 I(for spinning of rod)\omega^2 + 1/2I(for dropping of rod)\omega^2
 
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I'd suggest that there is only rotational kinetic energy to consider.

And it gets fed by the PE of the center of mass doesn't it?
 

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