Can I set my own bindings?

VtSkier wrote:
Walt wrote:
VtSkier wrote:
Walt wrote:

I cannot find a single definition of torque that
doesn't require motion that is either happening
or is about to happen.


That's odd, since I've only posted it about 5 times. Here it is again:

T = r x F

where F is the force and r is the moment arm vector.

Now, what, exactly, is in motion here? A force, acting on a moment
arm produces torque. We agree that it's possible for a force to exist
without motion. The above definition shows that a stationary force
will produce torque.

I really can't make this any clearer.

If I didn't know you better I'd say that you were just trolling.

//Walt

It goes to the definition of VECTOR. My reading, which I
posted, it that a vector has magnitude and direction.
Those are the qualities which create a vector, no?

Yes, a vector has magnitude and direction.


Magnitude is usually expressed as a unit of length.

Um....no. Vectors can have many different units. The electric field is
a vector with units of volt/meter. The magnetic field is vector with
units of ampere/meter. Momentum is a vector with units of
kilogram-meters/second. Acceleration is a vector. Angular momentum is
a vector. Angular acceleration is a vector.

There are thousands of vector quantities with all kinds of units.
Length is just one.


Force is expressed as a unit like pounds or newtons.
Force, by this definition is static. It takes
movement to make force into work. Or torque.

You lost me again.

So what part of T = r x F requires motion?

//Walt

Walt wrote:
VtSkier wrote:
Walt wrote:
VtSkier wrote:
Walt wrote:

I cannot find a single definition of torque that
doesn't require motion that is either happening
or is about to happen.


That's odd, since I've only posted it about 5 times. Here it is again:

T = r x F

where F is the force and r is the moment arm vector.

Now, what, exactly, is in motion here? A force, acting on a moment
arm produces torque. We agree that it's possible for a force to
exist without motion. The above definition shows that a stationary
force will produce torque.

I really can't make this any clearer.

If I didn't know you better I'd say that you were just trolling.

//Walt

It goes to the definition of VECTOR. My reading, which I
posted, it that a vector has magnitude and direction.
Those are the qualities which create a vector, no?

Yes, a vector has magnitude and direction.


Magnitude is usually expressed as a unit of length.

Um....no. Vectors can have many different units. The electric field is
a vector with units of volt/meter. The magnetic field is vector with
units of ampere/meter. Momentum is a vector with units of
kilogram-meters/second. Acceleration is a vector. Angular momentum is
a vector. Angular acceleration is a vector.

Yes, and although I haven't looked up each of those units,
each one that you note has a unit of length as a component,

Yes a vector has magnitude and direction. Each of the units
you note are vector quatities, that is, vector is a
component of each.

You've just shown a bunch of units, each of which has length
as a component.

There are thousands of vector quantities with all kinds of units. Length
is just one.


Force is expressed as a unit like pounds or newtons.
Force, by this definition is static. It takes
movement to make force into work. Or torque.

You lost me again.

So what part of T = r x F requires motion?

r, the vector. It has length (magnitude) as a component.

//Walt

VtSkier wrote:
Walt wrote:
VtSkier wrote:

It goes to the definition of VECTOR. My reading, which I
posted, it that a vector has magnitude and direction.
Those are the qualities which create a vector, no?

Yes, a vector has magnitude and direction.


Magnitude is usually expressed as a unit of length.

Um....no. Vectors can have many different units. The electric field
is a vector with units of volt/meter. The magnetic field is vector
with units of ampere/meter. Momentum is a vector with units of
kilogram-meters/second. Acceleration is a vector. Angular momentum
is a vector. Angular acceleration is a vector.

Yes, and although I haven't looked up each of those units,
each one that you note has a unit of length as a component,

sigh.

How about angular velocity, which has units of 1/second?

Vector != length

//Walt

klaus wrote:

The confusion is in the concept of total torque and component
torques. You can apply a component torque which does not cause
motion. In the case of the screw, the torque wrench applies a torque
(indicated by the reading on the wrench) and the screw applies an
equal and opposite torque such that no motion occurs until it breaks
free of the friction. The total torque until the screw moves is zero,
or there would be motion. However, the wrench is still applying a
torque, which is given by the reading.


I think you've got it. I was talking about component torque not net
(total) torque. VtSkier was talking about total torque (I think). So
we were talking past each other.

What VtSkier says is correct regarding total torque: If total torque is
non-zero, there's going to be motion (or more correctly, a change in
angular momentum). Conversely, if there is no change in angular
momentum, the total torque must be zero.

However, the way to calculate total torque is to add up all of the
component torques. These may be non-zero and yet still sum to a zero
result. So, you can have (component) torque without motion.



//Walt

VtSkier wrote:

So what part of T = r x F requires motion?

r, the vector. It has length (magnitude) as a component.

Um... length doesn't imply motion. Mt Trashmore has length, but it
isn't moving. Next?

//Walt

On Feb 19, 4:46 pm, VtSkier wrote:
Walt wrote:
VtSkier wrote:
Walt wrote:

I cannot find a single definition of torque that
doesn't require motion that is either happening
or is about to happen.

That's odd, since I've only posted it about 5 times. Here it is again:

T = r x F

where F is the force and r is the moment arm vector.

Now, what, exactly, is in motion here? A force, acting on a moment arm
produces torque. We agree that it's possible for a force to exist
without motion. The above definition shows that a stationary force will
produce torque.

I really can't make this any clearer.

If I didn't know you better I'd say that you were just trolling.

//Walt

It goes to the definition of VECTOR. My reading, which I
posted, it that a vector has magnitude and direction.
Those are the qualities which create a vector, no?

Magnitude is usually expressed as a unit of length.

Force is expressed as a unit like pounds or newtons.
Force, by this definition is static. It takes
movement to make force into work. Or torque.

If you multiply a unit by another unit, you have
created yet a third unit with the first two units
as components of the third.

If you multiply a force (weight) unit by a length
unit you have a third unit that has both weight
and length as components.

if the first two units were pounds and feet the
third unit will be pound-feet. This is a unit
that requires that a force be moved a distance.
If you specify the direction of the distance
and/or add leverage that unit is called TORQUE
as opposed to simply WORK. But the force still
has to move a distance.- Hide quoted text -

- Show quoted text -

On this one, sorry but you're just wrong. Consistently wrong. As in,
you've been wrong every single time, on every post in this thread.

Except for the few instances where you've agreed with Walt.

frankenskier wrote:
On Feb 19, 4:46 pm, VtSkier wrote:
Walt wrote:
VtSkier wrote:
Walt wrote:
I cannot find a single definition of torque that
doesn't require motion that is either happening
or is about to happen.
That's odd, since I've only posted it about 5 times. Here it is again:
T = r x F
where F is the force and r is the moment arm vector.
Now, what, exactly, is in motion here? A force, acting on a moment arm
produces torque. We agree that it's possible for a force to exist
without motion. The above definition shows that a stationary force will
produce torque.
I really can't make this any clearer.
If I didn't know you better I'd say that you were just trolling.
//Walt
It goes to the definition of VECTOR. My reading, which I
posted, it that a vector has magnitude and direction.
Those are the qualities which create a vector, no?

Magnitude is usually expressed as a unit of length.

Force is expressed as a unit like pounds or newtons.
Force, by this definition is static. It takes
movement to make force into work. Or torque.

If you multiply a unit by another unit, you have
created yet a third unit with the first two units
as components of the third.

If you multiply a force (weight) unit by a length
unit you have a third unit that has both weight
and length as components.

if the first two units were pounds and feet the
third unit will be pound-feet. This is a unit
that requires that a force be moved a distance.
If you specify the direction of the distance
and/or add leverage that unit is called TORQUE
as opposed to simply WORK. But the force still
has to move a distance.- Hide quoted text -

- Show quoted text -

On this one, sorry but you're just wrong. Consistently wrong. As in,
you've been wrong every single time, on every post in this thread.

Except for the few instances where you've agreed with Walt.

Oh? Well so far nobody has been able to show me where I'm wrong.

You included. You've simply said that I'm wrong and I'll discount
your statement until you can back it up.

Walt at least has been very patient in trying to show me by
his words and others (cites) where I'm wrong. And I STILL
haven't gotten it yet.

Klaus chimed in to try to shed a little light with his
explanation of component torque which may well be where I've
been trying to go.

It's very hard for me to say that the following is a false
statement:

"Total torque is zero, therefore there is no torque."

Component torque, WTF does that mean? A few more words
would be helpful here. Does it mean that there is a
component OF torque being applied? Since there are
only two parts to torque (at least in the case of
tightening or loosening a nut), force and vector,
does it mean that force only is being applied to the
lever arm which creates the vector until the nut moves
and the vector exists?

I've read elsewhere that this situation results in
a total torque value of zero.

Again, since there are only two components to torque,
and if a torque value of zero means the vector
component is zero since simple math tells us that
a value x 0 = 0, why isn't the statement:

"Total torque is zero, therefore there is no torque."

a true statement?

And then, what's all this dancing around about the
definition of vector? A vector is a quantity (not
an object, just something which is used to described
something an object does, namely move in a direction)
having magnitude and direction.

There is movement strongly implied in the definition.
Even more so that the simple definition of length.
Just because classroom explanations cannot show
movement, it doesn't mean there isn't any.

Further, I never learned calculus, except to
understand the concept that it is used to describe
movement and/or rate of change. If calculus is
the best way to describe torque, that in itself
implies that movement is a component of torque.

Nobody has tried to dissuade me that WORK/ENERGY
can exist without movement. All seem to agree that
WORK = FORCE x DISTANCE. That is: WORK is moving a
FORCE over a DISTANCE.

Yet when you add the simple concept of direction
to distance to create VECTOR which in turn creates
TORQUE = FORCE x VECTOR, you tell me that TORQUE
can still exist when the VECTOR value is zero.

Then along comes the twin concepts of Total TORQUE
and Component TORQUE.

So, two statements have been made:

VtSkier: "Without movement there is no torque."

Klaus: "Without movement, Total Torque equals zero."

What, pray tell, is the difference between these
two statements?

VtSkier wrote:

Component torque, WTF does that mean? A few more words
would be helpful here.


Ok. I'll keep trying.

Suppose you have a 20 ft long see-saw and place a 10 pound weight at the
right end. The torque from that weight is

T1 = r x F = 10feet x 10pounds = 100 ft-pounds

Now, place a second ten pound weight at the left end. It applies a torque of

T2 = r x F = -10feet x 10pounds = -100 ft-pounds
(the negative sign is because this torque is counter-clockwise)

To find the total torque, you add up the torque from each weight (i.e.
add up the component torques).

T = T1 + T2 = 100 + (-100) = 0

So, the total torque is zero, even though there is a non-zero component
torque from each of the two weights.


Of course, this is a very simple example and anybody could see that the
see-saw will balance. But a more complicated example, for instance
where there are 40 objects of different weights all at different
distances, would require more calculation. But the math is simple - just
compute the torque for each weight and then add them all up. Each
weight produces a torque - if the weights are distributed "evenly" the
total torque will be zero, but there are non-zero components.

Note that the concept of motion did not figure in any of these
calculations. Once we have calculated the total torque, we can observe
whether there will be motion. But in order to calculate the torque from
each weight you don't need to know whether it's in motion or not. It's
just the weight times the distance.


Does this help?

//Walt

Walt wrote:
VtSkier wrote:

Component torque, WTF does that mean? A few more words
would be helpful here.


Ok. I'll keep trying.

Suppose you have a 20 ft long see-saw and place a 10 pound weight at the
right end. The torque from that weight is

T1 = r x F = 10feet x 10pounds = 100 ft-pounds

Now, place a second ten pound weight at the left end. It applies a
torque of

T2 = r x F = -10feet x 10pounds = -100 ft-pounds
(the negative sign is because this torque is counter-clockwise)

To find the total torque, you add up the torque from each weight (i.e.
add up the component torques).

T = T1 + T2 = 100 + (-100) = 0

So, the total torque is zero, even though there is a non-zero component
torque from each of the two weights.


Of course, this is a very simple example and anybody could see that the
see-saw will balance. But a more complicated example, for instance
where there are 40 objects of different weights all at different
distances, would require more calculation. But the math is simple - just
compute the torque for each weight and then add them all up. Each
weight produces a torque - if the weights are distributed "evenly" the
total torque will be zero, but there are non-zero components.

Note that the concept of motion did not figure in any of these
calculations. Once we have calculated the total torque, we can observe
whether there will be motion. But in order to calculate the torque from
each weight you don't need to know whether it's in motion or not. It's
just the weight times the distance.


Does this help?

Yes, I also liked the four engine plane with engines rotating one way
on one wing and the other way on the other wing so that the component
torque would equal zero and the plane would fly in a straight line
without rudder input.

Help me out a little more with VECTOR here.

Vector has magnitude and direction, yes?
Of itself it has two "components"?

Can a vector have a value even though one of
its components is zero?

If so, then I can buy the concepts of

1) component torque, and

2) the ability of torque to exist even though
there is no movement.

In 2) above, I'm still troubled by the wrench
on the nut example. There is no component torque
here, yes? Yet there is no movement of the nut
until the force applied to the lever arm overcomes
friction to allow the nut to move.

In this case there is force, direction but no
magnitude/length.

The question is: Is a vector value calculated
as the product of magnitude and direction?

If so, then if there is no magnitude the
vector value is zero and the torque is zero.

If it is NOT the product and VECTOR can have
value even thought there is no movement and
TORQUE can therefore have value. We have
already determined that TORQUE is the product
of FORCE and VECTOR.

OK, I'm down to asking questions which means
you are softening me up.

I still have one more, though, not entirely
related to the present post's discussion.

You said early on that TORQUE and WORK were
not the same thing at all except that they
shared the units used.

I still have yet to puzzle out what is so much
different between the two EXCEPT that direction
of the FORCE applied over a length has been
added to create TORQUE as opposed to WORK.

The concept of horsepower was originally
formulated on the basis of WORK, that is
moving a FORCE over a LENGTH in a given
period of time. Yet today we use TORQUE in
place of WORK for formulating HORSEPOWER
in a rotating engine.

In any case, whether it's TORQUE or WORK,
HORSEPOWER = 550 FT-POUNDS/SECOND.
The difference being that you would use
RPM (or more correctly RPS) for the TIME
component.

I'm sure there are mathematical reasons for
the answers to come out the same even though
the components are slightly different, it
still says to me that the concepts of WORK
and TORQUE while slightly different, are very
closely related. This I think was the beginning
of the discussion.

VtSkier wrote:

And then, what's all this dancing around about the
definition of vector? A vector is a quantity (not
an object, just something which is used to described
something an object does, namely move in a direction)
having magnitude and direction.

Perhaps the definition and use of a vector is where the difficulty
resides? For this comment above apparently proposes that the torque
vector describes a movement direction? Not so: the torque vector
direction is at right angles to the rotational plane and hence any
movement - it's a vector cross product of the radius and the applied
force and points out of the plane of rotational motion.

In any case we can't do math in words; words are the wrong language.
Let's do skiing in words; so much easier, so: see elsewhere.