Quote:
Originally Posted by cdrazic93
1. This is straight from my textbook; "the quantity in rotational dynamics that takes into account both magnitude of the force and the direction and location at which it is applied is called the torque"(pg.175)welcome to rotational dynamics.
For a given torque, we get a different angular acceleration when mass is close to the axis of rotation than we get when it is farther away." This means that the drive shaft, that is a tube, has the mass at x distance away from the axis of rotation. The rotational quantity that describes the mass of the body and its distribution relative to the axis of rotation is called rotational inertia. (1)
2. The way he acts? He gets frustrated (and rightly so) that many people refuse to acknowledge math.
3. Actually if we're getting all technical on this; its rotational mass; not weight.
Rotational Acceleration=∑τ = I α
Torque is explained as t = r cross F
rotational inertia is I=integral from [a,b] of r^2 dm
work is described as w=dW/dtheta
angular momentum is described as L=integral from [a,b] of dVr cross p(r)v
now that we have that out of the way, the formula (from my textbook) of a rotating cylinder about an axis is I=(1/2)M(R^2+r^2). Where M is the mass. Mass is directly proportional to Inertia. "Unlike the mass, the rotational inertia of a body is not an intrinsic property of the body, but instead depends on the choice of axis of rotation. Just as the mass can be regarded as the property of a body that represents its resistance to linear acceleration, the rotational inertia represents the resistance of a body to angular acceleration." (pg. 175-176)
4. It's not theoretical opinion, when its math.
5. not based on "articles" he has read. It's based on math.
Academia is about as far from "internet science" as you can get.
work cited: Resnick, Robert, and David Halliday. "Rotational Dynamics." Physics. 5th ed. Vol. 1. New York: Wiley, 1992. 175, 176. Print.
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Yeah, schooled me. Too bad I have no idea what point you're actually trying to make. To be brief, you and me and stu all agree on the math and science. Is been this way since the beginning of the thread. Where our differences lie is in the statement by stu that the loss of said rotating mass can not be felt in a significant way. This is the hypothesis that I am rejecting:
The difference in mass between a stock and aluminum driveshaft is imperceptible.
That may even be true in a scientific study but in the real world with no controls, just knowing you installed such a component can cause you to feel a difference in your brain. The buttdyno effect. In this case however, all the math supports that losing mass on the driveshaft is beneficial anyway so...what are we really arguing here? Whether someone thinks it's worth it? People pay big money for stanced cars in this community. I think you guys are barking up the wrong tree. Perhaps you guys should go fight a battle worth fighting like HID retrofits on lifted 1990s trucks?