Understanding Torque: The Relationship Between Torque and Angular Momentum

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Torque is defined as the rate of change of angular momentum, expressed mathematically as Torque = (δ Angular momentum) / (δ time). The units for torque (N*m) align with the derived units from the equation, as a Newton can be expressed in terms of base SI units. The relationship between linear and angular motion is analogous, allowing for similar equations to be applied in both contexts. Understanding this equivalence is crucial for grasping concepts in rotational dynamics. The discussion emphasizes the importance of recognizing these parallels in physics.
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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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