Recent content by Kushwoho44

Hi, I was thinking about principal stresses and unfortunately this is a bit of a dark spot for me in my education. I understand principal stresses as the stresses that are present when the co-ordinate system is oriented such that there are no shear stresses, and only normal stresses. As such...

Hello forumites, I've been working with the following expression for the change in internal energy in an isentropic scenario. $$dU = n*c_v *dT = -pdV$$ However, I'm a bit stumped here, the left hand side of the expression (or middle rather), states the change in internal energy is the...

Hi, apologies, the '6' forces was a typo. Yes, I do think I have a clear picture now. So, at each point in space, there are six components of stress (3 shear, 3 normal). If we are interested in the forces/stresses on a surface, we take the dot product of the area/normal vector to get the result...

Orodruin, ChesterMiller, thanks for your responses. A follow-up: So, would I be correct to say that on each face in the illustrated control volume, there would be one normal stress and two shear stress components to the force on that area element. This is a special case as the face is normal to...

I have been trying to fully grasp the concept of the Cauchy stress tensor and so I thought I'd make a post where I clear up my confusion. There may be subsequent replies as I pose more questions. I am specifically confused at how the stress tensor relates to the control volume in the image...

Thank you - I have now fully grasped this concept with aid of your explanation. The principle missing cog for me was : In reverse, applying the work output of the heat engine (stored in a spring, say) to the same system operated in reverse (as a heat pump), the heat flows are the same but in...

Hi there, I hold an engineering degree and I was just reviewing a page on Wikipedia. This image specifically demonstrates the impossibility of two theoretical heat engines having different efficiencies between two heat reservoirs. The full Wikipedia page can be found...

Thanks guys! That makes so much sense.

Hi, As is commonly known, u = u(T,v) h = u(T,p) I've worked with some maths proofs of this a while ago, but do you guys have an intuitive way of understanding this without the maths, that is, why the state function for internal energy is defined by intensive volume and enthalpy with pressure...

Homework Statement EDIT: DO NOT READ. I SOLVED IT.[/B] The collision in this problem acts at point C and acts a purely horizontal force in the inertial frame of reference. Homework Equations The Attempt at a Solution I understand the maths that is at work here, when we resolve the force...

Okay, that makes sense. I have, to this far, thought of the pressure as driving the fluid flow. Thus, I would've thought that the conservation of momentum equation applies: p1A + p1A*V1^2 = p2A + p2A*V2^2 Though, it seems that we need to introduce a 'thrust' component. I don't really...

Homework Statement The attempt at a solution Hi all, I am tasked with finding the static thrust generated by this convergent-divergent nozzle. The stagnation pressure is known the inlet. Now, personally, I would've thought drawn a control volume around the entire nozzle. And then said...

Thanks a lot Chestermiller, this makes sense. Thanks for the help!

The experiment is passing air through a wind-tunnel and keeping a ball of diameter D in the center and then plotting the relevant dimensionless groups against each other. The parameters have units: V = ms^-1 D = m Drag = Newtons omega = rad/s

Homework Statement Hi guys, I need to explain the outlier point here, which has been shaded in the excel spread sheet when comparing the two dimensionless groups, The dimenionsless group, drag-coefficient is given by Drag/(density*V^2*D^2) and dimensionelss group, spin parameter, is given by...