Ummm... help?[Physics and Vector calculus involved]

[Amele]

Believe it or not, that proof was never proven in calc 3... not to my memory or notes anyhow.

which prof did you have? I remember some of pitt's courses proved it and some just sort of said 'this is how this works'.

[Creeps]

I'm just trying to pass so I can get back to my sweet, sweet social sciences, where I can understand things and actually have some kind of input into what the hell is going on. I'm fine with derivatives, I suck at differentiation :[

[Blarg]

Who wants to answer this question for me

A 3kg block is dragged over a rough horizontal surface by a constant force of 16N acting at an angle of 37 degrees above horizontal. The speed of the block increases from 4m/s to 6m/s in 5m displacement. What was the work done by friction.

I'm not exactly sure how to relate friction to that information since the only friction formula i see is (coefficient of friction x normal force = Ffriction) (static or kinetic depending on coefficient used)

[Amele]

Who wants to answer this question for me

A 3kg block is dragged over a rough horizontal surface by a constant force of 16N acting at an angle of 37 degrees above horizontal. The speed of the block increases from 4m/s to 6m/s in 5m displacement. What was the work done by friction.

I'm not exactly sure how to relate friction to that information since the only friction formula i see is (coefficient of friction x normal force = Ffriction) (static or kinetic depending on coefficient used)

figure out how fast the block should be going after moving that distance on a frictionless surface, then determine how much work you'd need to reduce that speed to 6m/s. that's the work that the friction did. you won't actually need to know the coefficient.

[Max™]

My rod is assumed to be infinitely long.

Huh, huh huh... penis.


I've actually got a question which I wouldn't mind having some calculus minded people consider.


Is there any way you can think of to calculate the tension that a spring of some arbitrary material would have when stretched 24 Billion light years?

[Kaylia]

My rod is assumed to be infinitely long.

Huh, huh huh... penis.


I've actually got a question which I wouldn't mind having some calculus minded people consider.


Is there any way you can think of to calculate the tension that a spring of some arbitrary material would have when stretched 24 Billion light years?

T= k*c*24billions >_> I dont know

[Epical]

BG's resident math whiz has shifted from Aurik to Woozie.

[Charla]

My rod is assumed to be infinitely long.

Huh, huh huh... penis.


I've actually got a question which I wouldn't mind having some calculus minded people consider.


Is there any way you can think of to calculate the tension that a spring of some arbitrary material would have when stretched 24 Billion light years?

How arbitrary are we talking? Because you might have to do some interesting things to the definitions of "spring", "stretch" and "material" in order to use something resembling matter and still have a question that makes sense.

[Salazar]

http://gaygamer.net/images/vectorman.jpg

[yayaok]

this is some fucked up shit im so glad im majoring in language

[Woozie]

Language is way harder than math/physics x_x

[Mizango]

Language is way harder than math/physics x_x

I was good at all 3 oddly enough. I somehow failed Library and PE lol. I can see the PE thing, because if were weren't playing Football or Basketball I would just go to lunch for the 3rd time :3

BG's resident math whiz has shifted from Aurik to Woozie.

Yeah Woozie is a monster at Math.

[Jodwahh]

http://i38.photobucket.com/albums/e1...500_AA240_.jpg

That's more my idea of learning calculus.

[heartslaught]

Amele, I had Klimas for calc 3. I can't remember if he exactly proved the 'beeline' as we refered to it in there. All I remember is walking away knowing that the gradient was the shortest path between two points. Outside of that, can't remember much, and my notes don't show it (though it wouldn't be the first time that in a class I didn't put something in my notes). Not like via engineering physics I saw any calc 3 until I left the program anyhow x.x. Probably why I'm still slightly rusty, didn't use it in a constant fashion to ingrain it.

Edit:
these are the days where I wish I had a damned solution manual to this stuff T_T. Going off your confidence is a good thing, but at times there are just blocks that a good push over now will lead to the ability to climb over the larger ones later, oye...

[Woozie]

All I remember is walking away knowing that the gradient was the shortest path between two points

You're getting "gradient" confused with "geodesic" (which isn't surprising because Classical mechanics books throw those two words around a lot and it's easy to get terms confused).

A geodesic is the shortest distance between two points. A gradient is what's produced when the del operator operates on a scalar field, producing a vector who's direction is that of maximum increase in the scalar field.

[Max™]

Well, I was more looking for how you would calculate say, a planck length object stretched to 24 Billion light years (I have the exact power of planck lengths written down somewhere, it's like 10 ^80 or something absurd), so I could insert different material tensions to test an idea I've been kicking around.

Just for argument, let's assume the tensile strength is that of steel, but it won't break when stretched that far, if that's sensible to assume.

[Charla]

Well, I was more looking for how you would calculate say, a planck length object stretched to 24 Billion light years (I have the exact power of planck lengths written down somewhere, it's like 10 ^80 or something absurd), so I could insert different material tensions to test an idea I've been kicking around.

Just for argument, let's assume the tensile strength is that of steel, but it won't break when stretched that far, if that's sensible to assume.

In any event, it appears the spring constant would not be involved, and that you're actually stretching the definition of matter more than anything else. What would a planck length object be like anyway? Isn't that smaller than any observed subatomic particle? And do subatomic particles even have anything remotely similar to material tensions? Perhaps we could simply get around your problem by calculating the probability that a theoretical unbound particle one planck length in size would have a position 24 billion light years away from its previous observed position. That's how quantum mechanics works, right?

[Max™]

Not working from the quantum side.

Ok.

Perhaps this would make it easier.

Consider an object roughly 3000 Kilometers long, with the bending resistance of steel, but perfectly ductile, stretched 24 Billion light years.

[Amele]

You're getting "gradient" confused with "geodesic" (which isn't surprising because Classical mechanics books throw those two words around a lot and it's easy to get terms confused).

A geodesic is the shortest distance between two points. A gradient is what's produced when the del operator operates on a scalar field, producing a vector who's direction is that of maximum increase in the scalar field.

in her defense, I had klimas for calc 3 the first time too, and he wasn't really any good (I ended up repeating it with another prof but for different reasons; turned out the uni I was coenrolled in during HS had a different organization to their calc classes, and I had basically missed all of pitt's Calc 2, so I was hopelessly lost in 3.. lol ) he didn't prove anything, really, and was very bad about mixing up terms.

I'm not sure why he was still teaching it really, except that everyone and their uncle needed calc3 to graduate so they had alot of sections.

[Max™]

The rod is assumed to be infinitely long.

For some reason, I want to sig that.