Recent content by mfig

In a tensile test, the onset of yielding will show on practically the entire cross-section. So, spotting the point at which the force-displacement curve deviates from linear is relatively easy. For bending, the situation is different. In bending, yield begins at the portions of the beam furthest...

My bachelor's degree is in physics/mathematics. I studied these because I always wanted to understand how the things in the world work, and I thought physics was pretty much the key to everything. After graduation, reality set in and I quickly figured out it was grad school or a low-paying job...

Hello, I think a general demonstration could be given along these lines. Consider a general closed system operating between some heat source (possibly variable temperature ##T##) and the environment (temperature ##T_0##) as it evolves from state 1 to state 2. For this case we have: Energy...

Hello, I am looking to purchase laboratory samples for mechanical testing. For example, Charpy impact test samples and standard tensile test samples. Does anyone have a recommendation for a reliable source? Thanks

Yes. If you think neglecting the vapor is untenable, we could replace the liquid with a hot solid. It is and it isn't the same. In the process you suggest, one would perform two actions: place a weight and add heat. In the process I suggest, these are accomplished in one action. I believe that...

I am not sure why my previous attempt was unclear to some. I may have made a mistake (or many) somewhere, and that could be the reason. Please let me know where the error is if that is the case. This is meant to help with a "concrete" example. I believe all three conditions are possible to...

Here is some way to get at this that doesn't rely on having solved the system, but on some general considerations and a guess that the solution is sinusoidal. I am not sure this is what you are looking for, but hopefully it will contribute. :smile: Let's say you had discovered by your...

I thought I would chime into say that there is a perhaps easier way to see the reason for the outcomes questioned on stack exchange. Say we have an ideal gas as the working substance. So, we know that the internal energy is a function only of temperature, and thus in an isothermal process the...

Use this isentropic relation for each gas (a and b) , setting ##T_{2a} =T_{2b}## and similarly for the final pressures. See what relation must obtain between initial quantities in order for that to hold. ##\frac{T_2}{T_1}= \left( \frac{P_2}{P_1}\right) ^{\frac{\gamma-1}{\gamma}}##

http://www.aciscience.org/docs/physical_properties_of_glycerine_and_its_solutions.pdf Table 42

They don't have to mention a regenerator for there to be one... this is a Stirling engine we are discussing, right?? That's what a Stirling engine is... I suppose that one could make the same design with 4 thermal reservoirs instead of a regenerator, but then that really is a different kind of...

These expressions are equivalent. Perhaps it will help you to see how. Recall that: ##a=constant \implies v(t)=at+v_0 \implies x(t) = \frac{at^2}{2} + v_0t + x_0 \tag{1}## Now the first expression for the average velocity is: ##\frac{x_2-x_1}{t_2-t_1}\tag{2}## If we use the third...

Look carefully at your first equation. It applies to a rectangular wall with area A=wy. ##F = \rho g w \frac{y^2}{2} = \rho g w y \frac{y}{2} = \rho g A \frac{y}{2} = \rho g A y_c## They are the same equation, it is just that the depth of the centroid of a rectangular wall with one edge at...

We really can't help it if someone uses a formula naively, can we? I am not sure what you want from me on this... perhaps some method to prevent people from misusing an equation? There is no such method. The best we can do is explain what the symbols mean and what they don't mean. There are...

Compare a horizontal spring to a vertical spring with mass. If there is no difference here, then there will be no difference for intermediate angles. For a horizontal spring, the equation of motion is given by: ##m\frac{d^2x}{dt^2}=-kx \tag{1}## Where x is the displacement from the...