On the nature of torque ....

[WhiteBlue]

Nm is actually not an energy unit. It is a unit for torque. I also tend to use g/s for fuel mass flow. It is better sized for technical calculations. kg/h is something they can probably better sell to the press and the general public. At least they have heard from those units.

[xpensive]

Nm is actually not an energy unit. It is a unit for torque.

Incidentally WB, mechanical energy is identified as Force (Newton) times Distance (Meter), which makes Nm as a unit.

Not to be confused with Torque, which is Force (Newton) times Lever (Meter), which also makes Nm as a unit.

[WhiteBlue]

True, but very unusual to me. I do prefer the unit J for energy and Nm for torque although they are both kg m2/s2.

[xpensive]

True, but very unusual to me. I do prefer the unit J for energy and Nm for torque although they are both kg m2/s2.

Not to the mechanical engineer, force times distance for energy and force times speed for power is most useful in my world.

Having said that, I typically translate it to kWh and kW in the end anyway, so that my superiors can relate to it.

[wuzak]

True, but very unusual to me. I do prefer the unit J for energy and Nm for torque although they are both kg m2/s2.

Not to the mechanical engineer, force times distance for energy and force times speed for power is most useful in my world.

Having said that, I typically translate it to kWh and kW in the end anyway, so that my superiors can relate to it.

Work and energy both have units of Joules. The Joule is dimesnionally the same as Newton-Metres. Nm is used for torque, and it is not directly equivalent to J.

Ws = Watt-Second, I presume, in which case it is, in fact, a Joule.

[xpensive]

...
Work and energy both have units of Joules. The Joule is dimesnionally the same as Newton-Metres. Nm is used for torque, and it is not directly equivalent to J.

Ws = Watt-Second, I presume, in which case it is, in fact, a Joule.

Having the last word on semantics, is it?

[WhiteBlue]

The interesting take away from this is the realization that torque is a form of energy, at least both share the same physical unit. That gives a better understanding to torque in engines to me.

A torquier engine provides more energy at a given engine speed. The result is you need not push that engine so hard to generate power. Easy to understand for such a complex concept as torque.

To elaborate a little further on this one could speculate that the 2014 power trains will be torquier over the whole rev range, which could be a performance advantage. The cars will probably be easier to accellerate out of corners on an equal peak power basis. It sounds strange for turbo engines but these units will probably drive more like big NA engines.

[bhall]

That explains a lot.

[xpensive]

The interesting take away from this is the realization that torque is a form of energy, at least both share the same physical unit. That gives a better understanding to torque in engines to me.
...

Not exactly, I can easily produce 500 Nm of torque with my bare hands and a decent pipe-wrench, but without angular movement there's no energy "produced" and without angular velocity no power whatsoever.

Anyway, I still believe that the FIA should have presented the new regulations with units that people can relate to;

- When people buy hybrid and electrical cars, charging capacity is in kWh, not MJ, just like when they pay their electrical bill.

- Nobody thinks of flow as in kg/h, but in liters per minute, m^3 per hour or day and for smaller flows cc per second.

I think a 1 kWh storage and 38 cc/second flow limit at 20 C (not 293.16K) would have been the way to present the new rules. Gasoline has a thermal expansion coefficient of 950 x 10-6/K, meaning 1.9% over 20 K, but the engineers would know that.

But that's me.

[xpensive]

The interesting take away from this is the realization that torque is a form of energy, at least both share the same physical unit. That gives a better understanding to torque in engines to me.
...

Not exactly, I can easily create 500 Nm of torque with my bare hands and a decent pipe-wrench, but without angular movement there's no energy "produced" and without angular velocity no power involved whatsoever.

As for Torque's relation to Rotating energy and power;

Rotating energy = Torque (Nm) times Angular movement (radians).
But as radian is a dimensionless quantity, Rotating energy also becomes Nm, which is the equal of Ws or J.

Rotating power = Torque (Nm) times Angular velocity (radians per second).
But as radian is a dimensionless quantity, Rotating power becomes Nm/s, which is the equal of W or J/s.

And:
Linear energy = Force (N) times Distance (m), also gives Nm, which is the equal of Ws or J.

Linear power = Force (N) times Speed (m/s), gives Nm/s, which is the equal of W or J/s.

An example;
Drive a 2000 kg car with 200 kW at 72 km/h (20 m/s) and floor it at peak-power, you get 200 000/20 = 10 000 N of propulsion.

Disregard air-resistance, force is mass times acceleration, the car will get a 10 000/2000 = 5 /s^2 (0.5 g) acceleration.

All regardless of engine torque.

[xpensive]

It is situations like these that gives away your lack of technical understanding, just like when you concluded that torque was a form of energy, you can't simply waive a thesis from a university somewhere as eternal evidence to your point.

[WhiteBlue]

It is situations like these that gives away your lack of technical understanding, just like when you concluded that torque was a form of energy, you can't simply waive a thesis from a university somewhere as eternal evidence to your point.

What if you torque up a torsion spring? Don't you think that the torque represents an energy that you add to that mechanical system? Science is a funny thing. Perhaps my scientific understanding gets in the way of what you call the technical understanding. I would much rather discuss the merits of the source that I mentioned than having a debate about my understanding of technical matters.
I would like to add that such judgement comes across as a bit patronizing to me.

[wuzak]

It is situations like these that gives away your lack of technical understanding, just like when you concluded that torque was a form of energy, you can't simply waive a thesis from a university somewhere as eternal evidence to your point.

What if you torque up a torsion spring? Don't you think that the torque represents an energy that you add to that mechanical system? Science is a funny thing. Perhaps my scientific understanding gets in the way of what you call the technical understanding. I would much rather discuss the merits of the source that I mentioned than having a debate about my understanding of technical matters.

When you use a force of X Newtons and move an object Y metres you have performed work of X N* Y m = XY Nm = XY J Work = energy.

In the case of a torsion spring the energy stored is dependent upon torque and angle. While torque is analogous to force, angle is analogous to distance. Angle is dimensionless, while Torque has the dimensions [M][L]^2/[T]^2.

Force has the dimensions [M][L]/[T]^2 and distance has the dimension [L[, so force x distance = [M]{L]^2/[T]^2.

[ringo]

As for the torque discussion, it is energy in the true sense. It is potential energy.
It probably wont translate directly to certain forms of energy still, because there is another side to it that i will mention later.

To illustrate, an engine doesn't produce torque if it doesn't have a resistive load. It's until it is resisted does it demonstrate torque.

White blue mentioned a spring, and It's like a spring in truth. It doesn't produce spring energy if it's not loaded. And a system can be in a state of torque until there is change in load. You can balance a torque arm for a million years and un balance it and it creates a moment; similar to unloading a spring.

Notwithstanding, I'm not sure how whiteblue is applying the concept, but he is not really 100% wrong. The units do ultimately describe the concept of energy. A torque only exists with some kind of resistance. In fact it can only be measured with a resistance, usually of equal magnitude. So it must be a potential energy.

However the discrepancy with WB ideas, is that torque is actually a vector quantity. It's direction does matter.
For energy this is not the case, energy is not a vector quantity because direction or orientation doesn't affect it's state or interaction. It's state is purely related to magnitude.
That's the main difference, and if you remember vector math it would make more sense when compared to energy.

This is my thought process anyway, so correct me if there's another viewpoint.

[WhiteBlue]

Thank you Ringo for your thoughts. What triggered my idea that torque, work and energy are all the same is the fact that they are all measured in the same physical units in the SI system Nm. That is a dead give away. Primitive thinking indeed but it can't be any other way.

High school also had something to do with it. I remember a very simple mechanical experiment. A ball gets released to run down a U shaped path. At the starting point the ball has potential energy according to its height. Running down it looses that potential energy and converts it into kinetic energy so that at the bottom of the curve it has no potential energy at all. When it runs up the uphill curve it trades kinetic energy again for potential until it comes to the point where the kinetic energy is zero again. The conversion process naturally is not loss less. The entropy must increase and so you loose a bit of energy to heat with every conversion cycle. A very simple thing really.

But the simple law of the energy balance is applicable for every type of energy conversion we do. If we convert chemical energy of a fuel to mechanical energy or electrical energy we always pay the price for the conversion and for increasing the entropy by heat losses. If you load and unload a battery, pump up and unload an air sprung accumulator or transform electric energy from high to low voltage. You always pay the price. It must be the same for engine torque and it clearly is the case.

When you apply torque to a crank shaft you cause an angular deformation to it which depends of the elastic properties of the system. That obviously is a form of potential energy which is comparable with the stroke of any linear spring. When you relax the spring you get kinetic energy. While you load or unload the system it also heats up like any other energy converting mechanical system would do. Hence torque unquestionably is potential energy.

Some types of energy can have vector qualities and some don't. Torque can be clockwise or anti clockwise in a polar coordinate system. Potential energy can exist in polar and carthesian vectors. Electric energy can be static or dynamic depending of the current being articulated or not. So in my view it is irrelevant if an energy form has vectoral or dynamic qualities. It remains energy and is subject to the thermodynamic law. Thank you for following my musings so far.