Simple angular acceleration problem

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SUMMARY

The discussion centers on calculating the angular acceleration of a 4-meter long rod hinged at one end and released from a horizontal position. The initial calculation of angular acceleration using the formula Ang. Accel. = (Tan. Accel.)/(radius) yielded 2.45 rad/s², but the correct answer is 3.6 rad/s². The discrepancy arises from not considering the torque about the pivot point, which is essential for determining the angular acceleration due to gravitational force acting on the rod.

PREREQUISITES
  • Understanding of angular motion and acceleration
  • Familiarity with torque and its calculation
  • Knowledge of gravitational force and its effects on rigid bodies
  • Basic principles of rotational dynamics
NEXT STEPS
  • Study the concept of torque and its relation to angular acceleration
  • Learn how to apply Newton's second law for rotation
  • Explore the moment of inertia for different shapes, including rods
  • Investigate the effects of different pivot points on angular motion
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This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of rotational dynamics and angular acceleration in rigid bodies.

joseg707
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Homework Statement


A 4 meter long rod is hinged at one end. The rod is initially held in the horizontal position, and then released as the free end is allowed to fall. What is the angular acceleration as it is released?


Homework Equations


Ang. Accel. = (Tan. Accel.)/(radius)


The Attempt at a Solution



(9.8m/s^2)/(4m)= 2.45rad/s^2

The answer is 3.6 rad/s^2.

I don't know what I'm doing wrong. Gravity is the only force acting on the rod, but there is something that I'm not taking into account. Can someone point me in the right direction please?
 
Physics news on Phys.org
Consider the torque about the pivot.

What is the force acting to create the angular acceleration.
 

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