Torque and equilibrium; concept problem

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SUMMARY

The discussion clarifies the relationship between net force and net torque in the context of equilibrium. It establishes that for a body to be in equilibrium, both net force and net torque must equal zero. The participants emphasize that while forces can create net torque, they can also sum to zero net force, illustrating that net force is the sum of individual forces rather than a standalone force. This understanding is crucial for grasping the principles of static equilibrium in physics.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concepts of torque and equilibrium
  • Knowledge of vector addition and force components
  • Basic grasp of angular motion and rotational dynamics
NEXT STEPS
  • Study the principles of static equilibrium in detail
  • Learn about the calculation of torque using the formula torque = Frsin@
  • Explore examples of net force and net torque in real-world applications
  • Investigate the implications of non-zero net force and net torque on object motion
USEFUL FOR

Students of physics, educators teaching mechanics, and anyone interested in understanding the principles of equilibrium in physical systems.

alpha372
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Homework Statement



I'm just trying to understand why the force from net torque isn't included in net force when considering equilibrium: Why isn't the force from torque part of the net forces acting on a body?

Homework Equations


if net force = 0 and net torque = 0 then the body is in equilibrium;
net force = ma, torque = Frsin@, where @ is theta


The Attempt at a Solution


It seems like the force required for torque should be part of the net forces acting on the body.
 
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"Net force" is not a force, it's the sum of individual forces. You can certainly have forces acting on something so as to create a net torque, yet those same forces add up to zero net force. For example: a vertical force to the right of center and an equal but opposite vertical force to the left of center.

And you can also have a net force on a body with zero net torque.
 
Doc Al said:
"Net force" is not a force, it's the sum of individual forces.

Agreed.

Your example helped me:
You can certainly have forces acting on something so as to create a net torque, yet those same forces add up to zero net force. For example: a vertical force to the right of center and an equal but opposite vertical force to the left of center.

Thanks.

So from this I now believe that the force from the torque actually is considered in the net force acting on the object. Now I am starting to understand why both net force and net torque need to be included for equilibrium.
 
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