One of you physicists

[Mikkel]

Except lbs/ft ain't correct.

Might be common shorthand, but the proper unit is lbf·ft

As I said - Imperial units, I couldn't possibly care less...

[Forest]

While multiplication may be commutative - the vector product (x) is not.

In this case - distance (taken from the centre to the circumference) and force being vectors - the following is true:

distance x force = -force x distance

Yes that is true. Though if your engine is rotating backwards, you've likely got bigger problems than the orientation of the torque vector.

[Whynot]

Fuck knows what a Newton is…

About 9.81kgs at sea level ...

[Forest]

About 9.81kgs at sea level ...

I think a weight of 1kg would generate a force of 9.81N under the earth's gravity.

So 1N = 1 / 9.81 = 0.102 kg

About the same as a small apple!

[Mikkel]

1 Newton is the force required to accelerate 1 kg to a speed of 1 m/s inside the timespan of 1 second.

Just like 1 Joule is the energy required to exert a force of 1 Newton over the distance of 1 meter.

And that is the beauty of the SI units (metric if you will) that you do not, generally, need any conversion factors in your equations.

[Bass]

Putting it in everyday terms - a Newton is roughly the force required to close a matchbox

[avgas]

In this case - distance (taken from the centre to the circumference) and force being vectors - the following is true:

distance x force = -force x distance

Funny thing was i had the same argument with a physics lecturer once, he said i was both wrong and right.
His argument stated that common sense (not physics) states that distance can also be a vector. As distance quite often is in relation to a position/destination.
It sadly made sense, as you never say to someone - walk 5 meters away, you always tell them "walk over there" or more specifically "walk 5 meters away from me in that direction".
He then told us not to remember this at exam time as he would fail us.
Goes to show that maths and theory sometimes make a horrible couple.
I found it ironic that we use this maths in dynamic systems however because a=-a in some circumstances just for the maths to work.

[Fooman]

Not to throw a spanner in the works - but one valid objection towards the Imperial (lb-ft) units compared to metric (Nm) units is the fact that if the gravitational acceleration changes between to locations the Imperial unit changes - where as the metric unit will remain constant.

Ahh, you have yet to be exposed to the imperial unit known as lbf (pound-force) Tis the equivalent of the newton (and is currently defined as a multiple of the newton). The mass unit derived from the lbf is amusingly known as the slug (with derivatives known as the slinch (slug-inch) = 12 slugs), although the pound mass (lbm) is more commonly used - and the change in weight force from a lbm in the gravitational field is what you are discussing.

Cheers,
FM

[MisterD]

Is this a hardware or a software problem.

Sorry...that's mechanical engineering not physics.

Meh. Everything is a branch of physics.

[The Stranger:Me]

So does any of this pedantic bullshit shit about pounds feet or foot pounds feets pounds change the performance of the bike?

No such thing as a simple question on KB is there?

Get out and ride for fucks sake!

[Mikkel]

Funny thing was i had the same argument with a physics lecturer once, he said i was both wrong and right.
His argument stated that common sense (not physics) states that distance can also be a vector. As distance quite often is in relation to a position/destination.
It sadly made sense, as you never say to someone - walk 5 meters away, you always tell them "walk over there" or more specifically "walk 5 meters away from me in that direction".
He then told us not to remember this at exam time as he would fail us.
Goes to show that maths and theory sometimes make a horrible couple.
I found it ironic that we use this maths in dynamic systems however because a=-a in some circumstances just for the maths to work.

I'm not sure if I follow what you are saying here.

However, the vector calculus is complete and describes all classical mechanical systems completely. Any spatial position will be described by a vector - and any change in position will be described as a vector that is the difference between the two position vectors.

Of course, it is often easier to just forget about the vectors and just work with the scalars. However, if you want the problem and solution defined with absolute clarity vectors are the go.

Ahh, you have yet to be exposed to the imperial unit known as lbf (pound-force) Tis the equivalent of the newton (and is currently defined as a multiple of the newton). The mass unit derived from the lbf is amusingly known as the slug (with derivatives known as the slinch (slug-inch) = 12 slugs), although the pound mass (lbm) is more commonly used - and the change in weight force from a lbm in the gravitational field is what you are discussing.

Next we'll be talking about poles, stones and farthlings - I'm quite serious when I say I have no time for the imperial units. The imperial units were awesome in a world where there were no calculators, computers, etc. - however today they are absolete.

Meh. Everything is a branch of physics.

...or psychology, it really depends upon what your perspective is. (Personally I agree with you though.)

[jrandom]

... today they are absolete.

... but the need for automated spelling checkers will endure, yea, even unto eternity?

Meh. Everything is a branch of physics.

[MisterD]

Youdaman for the cartoons entcha.

As the truism has it, when you get to university:-

Biology becomes Chemistry
Chemistry becomes Physics
Physics becomes Mathematics
and Mathematics....becomes f-ing impossible.

[Mikkel]

Well, you know what they say - mathematics are to physics what masturbation is to sex...

[Big Dave]

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