Calculate the torque on a rigid body

AI Thread Summary
Calculating the torque on a rigid body requires specifying an origin, as torque is defined relative to a coordinate system. Without an origin, only the vector part of torque exists, lacking direction and magnitude, which cannot be computed. The discussion highlights that transformations in physics, such as from manifold to manifold, necessitate an origin for accurate calculations. An example involving Earth's rotation illustrates the importance of this concept. Understanding these principles is crucial for anyone studying physics.
DNA
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Can someone please tell me if it is possible to calculate the torque on a rigid body without specifying the origin?
 
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DNA said:
Can someone please tell me if it is possible to calculate the torque on a rigid body without specifying the origin?
:smile: if you think about it a torque vector is oriented in the 3D-Euclidian space. the point of orientation is relative to some orgin in a chosen coordinate system. Now if you take the coordinate system away then you just have the vector part of the torque. this would imply that the direction and magnitude of the torque would be assumed and not computed, because the torque equation doesn't allow it to calculated without the origin specified(i.e. transformations from manifold-to-maniflold can occur). therefore, the torque cannot be computed without an origin, because it would cease to exist as a torque vector.this might not seem so obvious, but try the following problem and take away the origin from your coordinate system and try the same problem with the origin in the coordinate system(hint: use spherical coordinates). think about the torgue developed by the rotation of the Earth go through the calculation. keeping what I previously said in mind one should realize the validity of this rationalization. :smile:
 
I think that i understand, manifold to manifold transformations,spherical coordinates! I am only beginning my physics journey, it would seem that i have a long way to go.
 
Hello everyone, Consider the problem in which a car is told to travel at 30 km/h for L kilometers and then at 60 km/h for another L kilometers. Next, you are asked to determine the average speed. My question is: although we know that the average speed in this case is the harmonic mean of the two speeds, is it also possible to state that the average speed over this 2L-kilometer stretch can be obtained as a weighted average of the two speeds? Best regards, DaTario
This has been discussed many times on PF, and will likely come up again, so the video might come handy. Previous threads: https://www.physicsforums.com/threads/is-a-treadmill-incline-just-a-marketing-gimmick.937725/ https://www.physicsforums.com/threads/work-done-running-on-an-inclined-treadmill.927825/ https://www.physicsforums.com/threads/how-do-we-calculate-the-energy-we-used-to-do-something.1052162/
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