@bobble Help?

here

Okay

So this is about the guy that's in a spinning thing, and the floor drops out but the guy doesn't fall through

"Carlos (mass m) enters the carnival ride called the “Rotor.” The ride begins to rotate, and once Carlos has reached speed v, the floor drops out and he does not slip. "

For the FBD, is it just F_g and... F_c? Wait no, you said F_c is a net force

It's not centrifrugal force, as much as I would like to say that's a "force"

What kind of force would point inwards, away from the wall?

Centripetal force?

Friction? But Carlos is not moving?

F_frict, F_app, F_norm, F_air, F_grav?

I'm pretty sure those are all the forces we have to know

So which is pointing in?

Yup

Force applied?

> away from the wall

is hint hint

Friction between carlos and the wall? Oh you said away from the wall

Wait is it static friction?

Nope, though static friction is on the FBD

Huh?? Then it has to be force applied

More hint: what kind of force points away from a surface that you're pressing against?

Oh. Normal force

yep

So F_norm in, F_grav down... what force would point up?

Friction, because friciton points in the direction opposite of where something moves

yep!

Huh

And that's the whole FBD

"Derive an equation for normal force"

Hm

Let me think

Friction must be greater than or equal to gravity in order for Carlos to not fall straight down

What would happen if friction was greater than gravity?

Oh, if friction was greater than carlos would slide up. So friction is equal to gravity

Yep.

Though that isn't needed to find normal force

but is important conceptually

Which is kind of counter-intuitve because friction moves against the direction of where something would move

So friction can never be greater than gravity in this context?

Nope

That's really weird to think

Static friction is <= μF_norm because it is only as strong as it needs to be

isn't normal force=F_g/(mu)? Or am missing something?

@bobble Ah, now that equation makes sense

Okay, but we're only dealing with F_norm right now

You said that F_norm is acting as a centripetal force, yes?

"Derive an equation for the normal force on Carlos"

for

Right?

@bobble Yes

Oh, so F_c=F_norm?

Ah

A more complete question would be "Derive an equation for the normal force on Carlos from the wall"

@PrinceNorthLæraðr yep

Ah, I see

So, can you do the derivation now?

Yup

yay!

Just take the variables of F_c and set it equal to F_N

I'm just skimming the assignment to see if there's any other questions I have

Okay yeah I have one more set of questions

"Scenario Consider a cone made of a material for which friction may be neglected. The sides of the cone make an angleθ with the horizontal plane. A small block is placed at point P. In Case 1, the block is released from rest and slides down the side of the cone toward the point at the bottom. In Case 2, the block is released with initial motion so that the block travels with constant speed along the dotted circular path."

"In Case 2, the block is released so that it travels with a constant speed along the dotted circular path. Is the block accelerating?"

What do you want help with?

Trying to figure out why/why not it would be accelerating

acceleration = change in velocity, yes?

what is velocity composed of?

Magnitude and vector

It would be accelerating right?

Because although the magnitude is constant

"magnitude" = speed

The vector (direction where it points) changes constantly

"vector" is wrong, should just be direction

@bobble Velocity= "speed" and "direction"

a vector has magnitude and direction

It's a vector quantity. Right

So is speed or direction changing?

Direction is technically changing, although incrementally

I watched the Khan academy video on it :P

It's changing enough to matter, and constantly

Right. But it if it's angular velocity, does it accelerate?

angular velocity? do you mean tangential velocity?

Velocity of "omega".

tangential velocity is speed in the tangential direction, but the tangential direction is constantly changing

@PrinceNorthLæraðr we ain't learned omega yet

@bobble Oh, really? I wasn't cough really paying attention in class, but I learned omega from strangely, pre-calc

I didn't take the pre-calc class at my school, but I did take Math 3 Honors, which is sorta-kinda precaly

Ah, I see. Yeah, we just started trig unit for pre-calc, and we began "omega"

So, I'm guessing this unit isn't about angular velocity yet. One less thing to think about

that the weird w-lookin' thing? my physics teacher says we're learning that later

Yeah, omega is the weird w. Actually I don't remember if we went over that in class

I don't think we did

"Derive an expression for the magnitude of the normal force exerted on the object in each case in terms of F g , θ, and physical constants as necessary."

I'm so bad with derivations ugh

Normal force is away from the surface, so for case one, it's just inclined planes

What about for case two? Is it just centripetal motion?

Since my dinner will be soon, would you prefer me just giving you the explanations or waiting until I have time?

(soon = now, as it turns out)

It's fine, I actually figured it out

I think

@PrinceNorthLæraðr yep

@PrinceNorthLæraðr yep, though taken the angle into account

@bobble Yeah, I think I got it. Thanks!

See you later

(gravity should cancel out the vertical component of normal)

back, in case you need it

since North commented on bobble's math handwriting I thought I'd share mine

nice and bubbly!

just a low res version of phone screenshot

alternative when writing quickly

thoughts? other than the one-size-too-large parentheses

I like the pi

thanks? i guess? :)

and it's much neater than some - trust me, I've graded my fair share of math work

you mind sharing your version of above formula? :)

I don't have a way to write, just a touchpad.

if that touchpad has a drawing thingy...