Something new: Torque vs. Power!

[afm199]

It's a cross product. The dot is there because the units are composed of distance and force and you need some way to tell the factors of the units apart, but it doesn't really denote multiplication in the sense of a multiplicative product of some numbers. Torque is equivalent to a composition of a norm of the amount of motion and the amount of stuff that's in motion. Which means that it's equivalent to energy, which is obvious if you pay attention to the fact that the composition of the unit is represented pretty much like the playskool formula for work.

Teal deer: Don't think about it too much. Torque isn't power but they transform into each other because math. Torque is how much stuff you can do, power is how quickly you can do stuff.

I had this discussion once about the WTC on Quora once. The guy was insisting that the incident was demolition. I urged him to calculate the amount of energy in 300 tons of jet fuel, as it is SEVEN times the amount of energy in TNT of the same weight. He just couldn't get it. He insisted that the TNT had much more energy, that it would have been necessary for TNT to bring the building down. I said, no, one gram of oil has seven times the calories that one gram of TNT has. The only difference is adding TIME to the equation. The TNT can combust extremely quickly, the oil much more slowly. The end result is the same, the oil puts out seven times the energy the TNT does. And the WTC output from the jet fuel alone was over a kiloton of TNT equivalent.

 

[Smash Allen]

I had this discussion once about the WTC on Quora once. The guy was insisting that the incident was demolition. I urged him to calculate the amount of energy in 300 tons of jet fuel, as it is SEVEN times the amount of energy in TNT of the same weight. He just couldn't get it. He insisted that the TNT had much more energy, that it would have been necessary for TNT to bring the building down. I said, no, one gram of oil has seven times the calories that one gram of TNT has. The only difference is adding TIME to the equation. The TNT can combust extremely quickly, the oil much more slowly. The end result is the same, the oil puts out seven times the energy the TNT does. And the WTC output from the jet fuel alone was over a kiloton of TNT equivalent.

So inline 4s are jet fuel and twins are TNT?

 

[afm199]

So inline 4s are jet fuel and twins are TNT?

I think of the twins as potato mashers and the I4's as blenders.

 

[Smash Allen]

I think of the twins as potato mashers and the I4's as blenders.

Fz-09 is the magic bullet then right?

 

[afm199]

Fz-09 is the magic bullet then right?

The Fz09 is the Breville

https://www.amazon.com/gp/product/B...ode=as2&tag=tcb121-20&linkId=JO6I3U7H4J4HYMJJ

 

[nickypoo421]

It's a cross product. The dot is there because the units are composed of distance and force and you need some way to tell the factors of the units apart, but it doesn't really denote multiplication in the sense of a multiplicative product of some numbers. Torque is equivalent to a composition of a norm of the amount of motion and the amount of stuff that's in motion. Which means that it's equivalent to energy, which is obvious if you pay attention to the fact that the composition of the unit is represented pretty much like the playskool formula for work.

Teal deer: Don't think about it too much. Torque isn't power but they transform into each other because math. Torque is how much stuff you can do, power is how quickly you can do stuff.

Pretty thorough stuff right here, but to be pedantic about the pedantry of it, as far as the units are concerned, it's multiplication. The cross product has the same result as multiplication in dimensional analysis.

 

[hattusilis]

The cross product is not the same as multiplication. It's a determinant. It's a binary operation that is the composition of other binary operations. Either way it has absolutely zero bearing on how the components of its operands are composed.

Dimensional analysis is written the way that it is because the law of composition for physical units is commutative. And nobody really bothers to write the identity for the units under that law of composition for some reason (probably for the sake of elegance).

 

[clutchslip]

I had this discussion once about the WTC...... I said, no, one gram of oil has seven times the calories that one gram of TNT has. The only difference is adding TIME to the equation. The TNT can combust extremely quickly, the oil much more slowly. The end result is the same, the oil puts out seven times the energy the TNT does. And the WTC output from the jet fuel alone was over a kiloton of TNT equivalent.

I think of the twins as potato mashers and the I4's as blenders.

Have I told you how much I love you, lately?

 

[LectricBill]

And this why I ride electric: torque whore.

But the jet fuel went up in a fireball outside a building that fell in its own footprint at free fall speeds and WTC 7 did the same even though it wasn't hit. But I'm not gonna use my torque to thread jack!

 

[nickypoo421]

The cross product is not the same as multiplication. It's a determinant. It's a binary operation that is the composition of other binary operations. Either way it has absolutely zero bearing on how the components of its operands are composed.

Dimensional analysis is written the way that it is because the law of composition for physical units is commutative. And nobody really bothers to write the identity for the units under that law of composition for some reason (probably for the sake of elegance).

Yes, you've made that clear multiple times. No one is arguing with you, and you're not the only one who's taken a basic vector calculus course and learned about the cross product.

You've missed the point. The appropriate units for torque are ([M][L]/[T]^2)*[L], not ([M][L]/[T]^2) cross [L]. You can't cross-multiply physical dimensions, so you are incorrect in your original diatribe on Nick's comment.

 

[DataDan]

Cutting through the authentic motofizzix gibberish...

Torque is rotational force. It's the vector product of force--the muscle you apply as you tighten that axle nut--and a radius vector from the handle where you're grasping the wrench to the center of the socket. Because force on the handle is perpendicular to a line to the socket, magnitude of the torque vector in this case is simply force * distance. The longer the wrench, the more torque you can apply to the nut with given muscle. Duh.

Torque can be confused with work because the two have the same units--force * distance--but they're different things. Work is force applied THROUGH a distance, not AT a distance. As you push a wheelbarrow full of bricks up a hill, you're doing work--applying force as you cover distance. Come to a stop (wheelbarrow still balanced on its single wheel) and you have to apply force to keep it from rolling back down the hill, but you're not doing work because you're not going anywhere.

Rotational work is rotational force (i.e. torque) applied through an angle (rather than linear distance). If an engine produces 50 lb-ft of torque through a single crankshaft rotation, it has done 50 * 2pi lb-ft of work.

Power is the rate at which work is done--work divided by the time it takes to complete. Using the same example, let's say the crankshaft rotation took .01 seconds (100 RPS or 6000 RPM). The rate at which the engine produces power, then, is 50 * 2pi lb-ft / .01 sec. Tap a few keys and that comes out to 31,416 lb-ft/sec. By definition, one horsepower is 550 lb-ft/sec, so that's about 57 hp.

 

[hattusilis]

Torque isn't force. It's equivalent (read equivalent, not "equal to") to work, but it's not work. Things can be equivalent but unequal. Torque is a force composed with some length. Check the formal definition (i.e. the formula), if you're unsure

This is fundamental group theory. More abstract algebra than vector calculus. In fact I'm not even really sure that a cross product needs to operate on vectors. Cross products operate on n-tuples and an n-tuple isn't necessarily a vector. I can't think of any specific examples where you can compute a cross product of n-tuples which aren't vectors, but that's not proof that a cross product must be a binary operation of vectors. A cross product is defined for vecotrs, but that's not the same thing as only being defined for vectors.

Torques are expressed as a number composed with some physical unit. Products, in general, are not necessarily multiplicative products and, by definition of the multiplicative product of two numbers, you can't really compute a multiplicative product of two physical units by a multiplicative operation on two numbers since it's a binary operation of numbers by definition. Physical units are allowed to have their own binary operations, but collections of physical units are disjoint from collections of numbers and a subset of physical units has fundamentally different properties from a subset of real numbers.

I'd use fancy looking summations but this server is retarded and doesn't seem to like it when I embed LaTexified stuff.

 

[nickypoo421]

Jesus Christ. Can you just concede that the SI unit for torque is a fucking Newton TIMES a meter?

No one here is benefitting from your increasingly obscure rants on mathematics.

 

[hattusilis]

Jesus Christ. Can you just concede that the SI unit for torque is a fucking Newton TIMES a meter?

No, because a meter isn't a number and the concept of a newton times a meter is sort of the same as a potato times a turtle. And, technically, the unit is a meter composed with a newton. Though I'm pretty sure that the law of composition under which a group of physical units is formed is commutative, so it's more of a convention than an actual necessity.

You could call the law of composition for a group of physical units unit multiplication if you want, but you really shouldn't make the mistake of conflating it with a binary operation on numbers Morty. Shit gets you all in trouble dawg.

 

[Killroy1999]

By unpopular demand...

In the OP's contrived example, the half-torque, equal-power engine was able to use only half its power, and--OMFG!--it was half as fast. When both could use full power, they were equally fast.

The best predictor of straight-line performance is power-to-weight ratio. The data points in the graph below are from nearly 20 years of Motorcycle Consumer News road tests. A similar graph showing torque-to-weight ratio is scattered all over the place because you have oddities like a Daytona 675, Harley Sportster, and Honda Gold Wing with nearly identical ratios, yet the Daytona is nearly 3 seconds quicker.

View attachment 484684

+1

 

[Killroy1999]

No, because a meter isn't a number and the concept of a newton times a meter is sort of the same as a potato times a turtle. And, technically, the unit is a meter composed with a newton. Though I'm pretty sure that the law of composition under which a group of physical units is formed is commutative, so it's more of a convention than an actual necessity.

You could call the law of composition for a group of physical units unit multiplication if you want, but you really shouldn't make the mistake of conflating it with a binary operation on numbers Morty. Shit gets you all in trouble dawg.

This is splitting hairs and not making a great point.

 

[hattusilis]

It's actually a pretty important distinction, bruised egos or no.

You know that you're onto the good stuff when you start talking math and somebody starts complaining about how you're splitting hairs.

 

[zixaq]

It's actually a pretty important distinction, bruised egos or no.

You know that you're onto the good stuff when you start talking math and somebody starts complaining about how you're splitting hairs.

Your "important distinction" doesn't matter in this context and nobody cares. Please take your mental masturbation elsewhere.

 

[DataDan]

Jesus Christ. Can you just concede that the SI unit for torque is a fucking Newton TIMES a meter?

No, because a meter isn't a number and the concept of a newton times a meter is sort of the same as a potato times a turtle. And, technically, the unit is a meter composed with a newton. Though I'm pretty sure that the law of composition under which a group of physical units is formed is commutative, so it's more of a convention than an actual necessity.

You could call the law of composition for a group of physical units unit multiplication if you want, but you really shouldn't make the mistake of conflating it with a binary operation on numbers Morty. Shit gets you all in trouble dawg.

This is splitting hairs and not making a great point.

It's actually a pretty important distinction, bruised egos or no.

You know that you're onto the good stuff when you start talking math and somebody starts complaining about how you're splitting hairs.

Whatever your level of mastery of the mathematics, you fail to grasp the physics. And it's really, really basic.

As I said before (and which you tried to dismiss with nonsense) TORQUE IS ROTATIONAL FORCE. It can be quantified as a tangential linear force multiplied by the radius at which it is applied. From the point of view of the axle nut being tightened, torque is the same if you're applying 50lb to a 2ft wrench or 100lb with a 1ft wrench.

And TORQUE IS NOT THE SAME AS WORK, EVEN THOUGH THEY ARE EXPRESSED IN THE SAME UNITS.

Torque is equivalent to a composition of a norm of the amount of motion and the amount of stuff that's in motion. Which means that it's equivalent to energy, which is obvious if you pay attention to the fact that the composition of the unit is represented pretty much like the playskool formula for work.

This is just gibberish. You formed syntactically valid English sentences that are a semantic nullity. You might get away with that on other forums, but not BARF.

 

[hattusilis]

No mastery of math. This is really basic algebra.

TTORQUE IS ROTATIONAL FORCE.

Nope. Check your units. A force composed with a distance is not a force. Them units ain't equivalent to units of a force


Do you understand the difference between equivalence and equality? Just because something confuses you (and people tell you that you're sooo smart) it doesn't mean that it's bullshit.

Incidentally, I got that nonsensical line about "amount of motion" from reading Newton's Principia.