Torque vs Energy. Same units, not the same thing

[SameSame]

https://postimg.org/image/g7wig8mgl/
https://postimg.org/image/g7wig8mgl/

The perfect explanation

Dutch high school physics pay off in later life eventually. But this also shows that torque does not equal energy. Torque is by definition stationary, it's in rest. It can have energy stored (like a spring), but that is something completely different.

Yes I must say that's a massive blunder on my part. I kept thinking about a net torque, and not just plain torque. But as you say, it could cause a potential energy in an object. (That energy value will depend on the modulus of the material and the moment of inertia)

[Jersey Tom]

JT, afraid I have to disagree. Torque is a force, a rotational or twisting force as you mentioned previously

I would make the case that if you were to mention the word 'force' to an engineer, physicist, etc. - the assumption is that you're referring to linear action.

So is torque = force? No.

Is torque a rotational force? Yes.

[dans79]

A classically trained physicist is not going to use the term torque, they are going to use the term moment, which is more general.

[Tim.Wright]

This was more fun when it was in the Mercedes team thread.

I know this is pretty pedantic stuff but I associate torque as a force. In fact I see all applications of rotational physics as an instantaneous application of a linear system.
A torque, to me, is what results when different parts of a single body are loaded with linear forces in different directions.
In the same way a rotational movement is just when different points on the same body move linearly in different directions.
A polar inertia is the sum of the linear inertial reactions of each mass increment at every point on a body.

[SameSame]

A classically trained physicist is not going to use the term torque, they are going to use the term moment, which is more general.

I'm not sure about the terms physicists use, but in in engineering terms a moment refers to the "twisting" about an axis lying on the cross sectional area of a member, where as torque is used when refering to the axis that runs through the body.

i.e. For a shaft the term torque would be used in the case of axis running through the shaft and the term moment would be used on the axis lying on the face of the shaft.

Edit: I'm being very general here, torques could of course be applied to the side of the shaft.

[Jolle]

and then back to how torque relates to horsepower:

given an engines torque and revolutions per minute you'll get (lets say, a F1 PU at 500Nm at 12.000 rpm)

12000/60 (to get revolutions per seconds)*6.28(two times pi, to get a meters of travel)*torque(500)= amounts of watts=628kW*1.36=854bhp.

[dans79]

I think its called a moment in physics, because the concept of torque starts to get a little ambiguous when you start talking about charged particles and what not.

[Jolle]

A classically trained physicist is not going to use the term torque, they are going to use the term moment, which is more general.

I'm not sure about the terms physicists use, but in in engineering terms a moment refers to the "twisting" about an axis lying on the cross sectional area of a member, where as torque is used when refering to the axis that runs through the body.

i.e. For a shaft the term torque would be used in the case of axis running through the shaft and the term moment would be used on the axis lying on the face of the shaft.

Edit: I'm being very general here, torques could of course be applied to the side of the shaft.

It's about a force on a single point with a circular direction. To make it measurable you need a lever. That's why the distance from the point is there. But it's all about force.

[SameSame]

A classically trained physicist is not going to use the term torque, they are going to use the term moment, which is more general.

I'm not sure about the terms physicists use, but in in engineering terms a moment refers to the "twisting" about an axis lying on the cross sectional area of a member, where as torque is used when refering to the axis that runs through the body.

i.e. For a shaft the term torque would be used in the case of axis running through the shaft and the term moment would be used on the axis lying on the face of the shaft.

Edit: I'm being very general here, torques could of course be applied to the side of the shaft.

It's about a force on a single point with a circular direction. To make it measurable you need a lever. That's why the distance from the point is there. But it's all about force.

Yes, but that circular direction is about (read: around) an axis. The axis it is acting about generally determines whether you call it a torque or a moment

[Jolle]

and then back to how torque relates to horsepower:

given an engines torque and revolutions per minute you'll get (lets say, a F1 PU at 500Nm at 12.000 rpm)

12000/60 (to get revolutions per seconds)*6.28(two times pi, to get a meters of travel)*torque(500)= amounts of watts=628kW*1.36=854bhp.

This by the way also shows how the last few V8 years were very restricted (on power).

With (without fuel flow restrictions) a engine torque is pretty much a constant, as long as you'll get the fuel/air mix right, it's always the same push on the pistons so in the old V10/12 days, more rpm equals more power.

The rev limit gave the formula a constant rpm, with a constant torque there was a hard ceiling on bhp.

In the new formula torque isn't constant anymore because above 10.500 rpm for every revolution you'll get less fuel so less torque. Instead of the torque staying flat, the power stays flat above 10.500 rpm.

[Jolle]

I'm not sure about the terms physicists use, but in in engineering terms a moment refers to the "twisting" about an axis lying on the cross sectional area of a member, where as torque is used when refering to the axis that runs through the body.

i.e. For a shaft the term torque would be used in the case of axis running through the shaft and the term moment would be used on the axis lying on the face of the shaft.

Edit: I'm being very general here, torques could of course be applied to the side of the shaft.

It's about a force on a single point with a circular direction. To make it measurable you need a lever. That's why the distance from the point is there. But it's all about force.

Yes, but that circular direction is about (read: around) an axis. The axis it is acting about generally determines whether you call it a torque or a moment

It's measured by moment force, with one side being "zero"

[SameSame]

Huh? The moment produces no force about the neutral axis.

Not sure what you mean by one side of a moment being zero?

[Jolle]

Huh? Do you mean that the moment produces no force about the neutral axis?

no, if you take the seesaw, you only have one side. You can make that same side still twice as long, and then you'll need half the force. That's why it's Nm.

[SameSame]

Huh? Do you mean that the moment produces no force about the neutral axis?

no, if you take the seesaw, you only have one side. You can make that same side still twice as long, and then you'll need half the force. That's why it's Nm.

What do you mean you only have one side?

Edit: A moment produces no force/stress on the neutral axis. That's a pretty well know fact.

[Jolle]

Huh? Do you mean that the moment produces no force about the neutral axis?

no, if you take the seesaw, you only have one side. You can make that same side still twice as long, and then you'll need half the force. That's why it's Nm.

What do you mean you only have one side?

Edit: A moment produces no force/stress on the neutral axis. That's a pretty well know fact.

oh i had the seesaw in my head, with Nm on both sides, not having a force on the pivot whatsoever. my bad