Combined rotational and translational motion

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SUMMARY

The discussion focuses on calculating the total kinetic energy of a long thin rod that rotates around an axis while also translating at a constant velocity. The mass of the rod is denoted as M, its length as L, and the translational velocity of the axis as Vaxis. The moment of inertia (I) for the rod is established as 1/3 M (L²). The total kinetic energy formula is confirmed as Total KE = 1/2 M (Vaxis²) + 1/2 I (w²), validating the combination of translational and rotational kinetic energy components.

PREREQUISITES
  • Understanding of rotational dynamics and moment of inertia
  • Familiarity with kinetic energy equations in physics
  • Knowledge of angular velocity and its relationship to linear velocity
  • Basic principles of mechanics involving rigid body motion
NEXT STEPS
  • Study the relationship between tangential and rotational velocities in rigid body motion
  • Explore advanced concepts in rotational dynamics, such as angular momentum
  • Learn about the applications of kinetic energy in mechanical systems
  • Investigate the effects of varying mass distributions on moment of inertia
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This discussion is beneficial for physics students, educators, and professionals involved in mechanics, particularly those studying rotational motion and energy calculations in rigid bodies.

e2m2a
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Homework Statement



I need to determine the total kinetic energy of a long thin rod relative to a laboratory frame which rotates around an axis at an angular velocity w and the axis moves at a constant translational velocity. The mass of the rod is M and the length of the rod is L. The translational velocity of the axis is Vaxis.

Homework Equations


Moment of Inertia, I, of rod is: 1/3 M (L sq) (This is because the rod rotates at one end).


The Attempt at a Solution


I believe the total kinetic energy should be: Total KE = 1/2 M (Vaxis sq) + 1/2 I (w sq).
Is this correct?
 
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e2m2a said:
[Moment of Inertia, I, of rod is: 1/3 M (L sq) (This is because the rod rotates at one end).


The Attempt at a Solution


I believe the total kinetic energy should be: Total KE = 1/2 M (Vaxis sq) + 1/2 I (w sq).
Is this correct?
Hello e2m2a
The moment of inertia is correct and addition of energies too. Is there some relation of the tangential and the rotational velocities. Remind that the endpoint velocitie for a whip is one mach. The maximum is there when the endpoint of the rods velocity L*w adds up to Vaxis.
greetings Janm
 

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