Semester one assignment: Find the angular speed

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SUMMARY

The discussion focuses on calculating the angular speed of a 1.5m thin rod that rotates downward from a vertical position before striking the floor. The key approach to solving this problem involves applying the principle of conservation of energy, rather than relying on rotational kinematics or treating the object as free-falling. The solution emphasizes the importance of understanding energy transformations in rotational motion to derive the angular speed just before impact.

PREREQUISITES
  • Understanding of conservation of energy principles in physics
  • Familiarity with rotational motion concepts
  • Basic knowledge of angular speed and its calculations
  • Ability to analyze motion using kinematic equations
NEXT STEPS
  • Study the conservation of energy in rotational systems
  • Learn how to calculate angular speed using energy methods
  • Explore the relationship between linear and angular motion
  • Review examples of rotational dynamics problems involving hinges
USEFUL FOR

Students in physics courses, particularly those studying mechanics, as well as educators looking for practical examples of rotational motion and energy conservation principles.

invadertak
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Homework Statement


A thin rod of lenth 1.5m is oriented vertically, with its bottom end attached to the floor by means of a frcitionless hinge. The mass of the rod may be ignored compared to the mass of and object ixed to the top of the rod. The rod, starting from rest, tips over and rotates downward. What is the angular speed of the rod just before it strikes the floor?

Homework Equations





The Attempt at a Solution


I need to find the time taken for the rod to hit the floor. I don't have enough information to use the equations of rotational kinematics without time. I can't use the equations of uniform circular motion, because the object is accelerating tangentially. I could break down the x and y motion of the object attached to the rod, but the conditions are not of free fall, surely? If I do treat the object as freefalling, it's very easy to get the time taken to hit the floor. Is that the correct way to get the time? Can I treat it as an object in free fall?
 
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Welcome to PF!

Hi invadertak! Welcome to PF! :smile:
invadertak said:
A thin rod of lenth 1.5m is oriented vertically, with its bottom end attached to the floor by means of a frcitionless hinge. The mass of the rod may be ignored compared to the mass of and object ixed to the top of the rod. The rod, starting from rest, tips over and rotates downward. What is the angular speed of the rod just before it strikes the floor?
…
I need to find the time taken for the rod to hit the floor.

No … just use conservation of energy :wink:
 
awesome!
 

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