Rigid body mechanics, solution seems incorrect?

In summary, the conversation discusses a problem and solution, where the gear E and rod OB are considered as a rotating rigid body. However, the equations of motion and moment are applied to the center of mass of the rod, G, instead of the center of mass of the rigid body. There is also a concern about an issue with the physicsforums page and the inability to attach anything.
  • #1
Amin2014
113
3
I've attached the problem and solution as picture. To my understanding, the gear E and the rod OB are taken together as the rotating rigid body. However, the equations of motion and (##∑F = macm##)
are applied to the center of mass of the rod, G, rather than the center of mass of the rigid body. Similarly, the moment is taken about G, and the mass of the rod is taken as m in the equations. Surely this can't be correct?
 
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  • #2
For the moment, there's an issue my my physicsforums page. The drop down menus don't function and I can't attach anything.
 

1. What is rigid body mechanics?

Rigid body mechanics is a branch of classical mechanics that studies the motion and forces of objects that are assumed to be rigid, meaning they do not deform or change shape under the influence of external forces.

2. What types of problems can be solved using rigid body mechanics?

Rigid body mechanics can be used to solve problems related to the motion of objects such as projectiles, pendulums, and rolling bodies. It can also be applied to engineering problems involving the design and analysis of structures and machines.

3. How is rigid body mechanics different from other branches of mechanics?

Rigid body mechanics differs from other branches of mechanics, such as fluid mechanics and continuum mechanics, in that it assumes objects to be rigid and does not consider the effects of deformation or fluid flow.

4. What are some common mistakes that can lead to incorrect solutions in rigid body mechanics?

Some common mistakes in rigid body mechanics include neglecting certain forces, such as friction or air resistance, not properly considering the distribution of mass in an object, and using incorrect equations or assumptions.

5. How can I improve my understanding and application of rigid body mechanics?

To improve your understanding and application of rigid body mechanics, it is important to have a strong foundation in mathematics, particularly in calculus and vector algebra. It is also helpful to practice solving a variety of problems and to carefully consider all forces and assumptions involved in each problem.

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