Recent content by erobz

It's not difficult, but I do recall "getting it"(I learned algebra mostly as an adult though). I teach my kids by balance scale type problems. There is an intuitive understanding about physical balance at a pretty young age. You might balance shapes with them, and you can use other balance...

The vertical pipe is the discharge. If there is a check valve at its base, we don't have to worry about dynamics of the flow into that tube (Eventually the filling process will halt). moving the vertical pipe left or right has no consequence as there is no friction damping to consider in the...

If there is doubt, couldn't we just compare the cited pump head of manufactured ram pumps to the theoretical ## \frac{\Delta p}{\rho g } = \frac{V^2 + Vc}{g} ## that we get from the Momentum Equation analysis? It's independent of design, its a hard (upper) limit using the water hammer theory.

I know the feeling very well. :smile:

The water stops flowing because someone slammed the gate closed. The pressure spike ( post sound wave beginning to travel toward the sump) work to open the valve back up. Then the system returns to its lower state of pressure once the wave has made it to the inlet of the sump(river). The valve...

Dimensionally it's inconsistent. So back to the drawing board. I guess its dimensionally ok. On second thought it appears to be the unsteady Bernoulli equation. But something isn't quite correct because it should be like in the following paper...

Ok, basically like a glass marble impacting a steel rod and the duration of impact tends to zero. (I.e normal force doesn’t have time to change the marbles direction from purely horizontal).

I would assume that if they are of comparable mass then the solution one gets from simplified analysis is horsecrap (far from observerable) anyhow... I also think its damaging to the learning process not to explore the simplifications we need to make in detail. So the best model must lie...

I wouldn't have asked if it was "clear".

Should maybe the author just restrict the domain of the analysis to rods significantly more massive than the ball so the angle of rotation is negligible over the duration of the impact?

The impulse is delivered over a duration of time, so on an off center hit, do we really know the balls direction? I'm imagining something like this is going to happen: The normal force will change magnitude and direction from ##N \rightarrow N' ##, and the ball doesn't have on obvious...

And to help you probe your understanding why do you think that is the case i.e. under what conditions is conservation of momentum applicable?

I think we can neglect radiation loss in comparison to convection heat loss, as ## q^{"}_{conv} = h ( T - T_{\infty})## is about an order of magnitude larger than ## q^{"}_{rad} = \sigma \epsilon ( T^4 - T^4_\infty)## using 226 F for ##T##. The far right side will be even cooler during the whole...

It's definitely a major jump in mathematical complexity, which is why it's likely glossed over in undergraduate coursework. So here is what is going on in a single plane wall that is subjects to your conditions: The purple, yellow, pink curves are ##T(x,t)## at some arbitrary times after the...

Oh, and just to be clear. As far as I understand this problem it is effectively asking "how long did it take for this plane wall system to reach steady state". At that point in time the thermal gradients are fixed across the materials, and they would just be linear. However, computing the...