Understanding Torque: The Relationship Between Torque and Angular Momentum

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SUMMARY

The discussion clarifies the relationship between torque and angular momentum, confirming that torque is indeed the rate of change of angular momentum, expressed mathematically as Torque = (δ Angular momentum) / (δ time). The units of torque (N*m) align with the derived units from the equation, as torque corresponds to the angular equivalent of Newton's second law (F = m*a). The conversation emphasizes the analogy between linear and angular motion, highlighting that understanding one can facilitate comprehension of the other.

PREREQUISITES
  • Understanding of Newton's second law (F = m*a)
  • Familiarity with angular momentum (L = Iω)
  • Basic knowledge of units in physics (N*m, kg*m^2*s^-2)
  • Concept of rotational motion and its equivalence to linear motion
NEXT STEPS
  • Study the derivation of torque from angular momentum equations
  • Explore the relationship between linear and angular kinematics
  • Learn about the applications of torque in rotational dynamics
  • Investigate the implications of torque in engineering and physics problems
USEFUL FOR

Physics students, engineers, and anyone interested in the principles of dynamics and rotational motion will benefit from this discussion.

24forChromium
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I read this article:
http://www.freestudy.co.uk/dynamics/gyros.pdf
at the bottom of page 2, it bolded text it is said "Torque = rate of change of angular momentum"

Is that right? It seems to suggest that Torque = (δ Angular momentum) / (δ time)
but the units do not appear to work out. Torque is in N*m, the right hand side's unit is kg*m^2*s^-2. I don't know anyway this can equate.

I might have missed something painfully obvious, but I can't see it right now, my head is fried from lack of sleep.
 
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A Newton is not a base SI unit. You can use Newton's seconds law (##\vec{F} = m\vec{a}##) to find out for yourself.
You'll see they do match.
 
Note that since F = dp/dt, the time rate of change of linear momentum, you should notice the angular equivalent of the expression for torque, i.e. T = dL/dt, the time rate of change of angular momentum. Torque is the "force equivalent" in rotational motion.

There is a completely analogous set of equations between linear motion and angular motion. If you can find the angular equivalent of a linear expression, then the angular kinematics is almost identical.

Zz.
 
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