Recent content by Uchida

I solved it by two methods: ----------------------------------------------------- First, by conservation of linear momentum, using the vector velocities of each particle: In the imminence of the impact, the velocity of all the three particles are the same, \vec v_0 = - \sqrt{2gh} \hat j...

@Steve4Physics Indeed, I can see what you have said. however, even if the disc has no angular speed, mathematical modeling should be done considering a "virtual bar" from the center of the disc to the point of instantaneous contact, which would eventually have angular speed (this angular speed...

Yes! I see! Thank you! I wrote ω= vr. This is not Correct. It should be v = ωr. What a silly mistake! :-p Therefore, the correct equation would be VP = ω_OA x r_A/O, which give the same result as the second approach. ω_OA = sqrt(3)/2 rad/s. So, what I assumed was correct after all: whenever...

Yes, the question is very poorly formulated. Right! I need to practice English as well as kinematics! :-p

Indeed, it is very confusing, and I am not able to model these problems right now. I am using Hibblers Book, Engineering Mechanics: Dynamics as reference for study. There is some problems like this, but no solved examples (or at least I haven't found them yet). Those with just bars are ok for...

First, I tried to model the disk-bar as a crank connecting rod, to the OA bar, and apply this: VP = VB + ω_BP x r_P/B, where P is the contact point between the disc and OA bar. I assumed VP = VP sin 30º i + VP cos 30º j (direction parallel to r_P/B), where r_P/B = sin 30º i + cos 30 j This...

Thanks for your answers. I see the mistake I´ 've made. Starting from H = U + PV: h = u + pv Then dh = du + p.dv + v.dp = 𝛿q + v.dp so, dh = 𝛿q only if the process is isobaric, where dp = 0 from the v.dp term.

Hi, Considering the question bellow from a government work selection process:Check the FALSE alternative on the use of thermodynamic properties. In a cylinder-piston type system, the variation of the enthalpy property (Δh) is usually applied to determine the heat (per kilogram) exchanged with...

Is there a limit on the minimum diameter that a collimated electromagnetic beam must have (lasers or masers), in terms of its wavelength, or it is possible to create a beam with its diameter smaller than its wavelength? I'm considering a colimated planar wave directly from the source, and not...

Ok, the rod is an analogy for "linear spatial distance". Since english is not my native language, I could not find a better way to express my problem. Let me try to put this question on other words: Does spacetime distortions near a black hole causes apparent length distortions if measured...

Thank you sirs for your answers. Aparently I formulated the question using a too mundane analogy, when all I want is a fundamental answer. So let me clarifly some assumptions before we can discuss the problem: Let assume that the bar is made with a very high youngs modulus and tensile...

If I make two rods with 1 meter length here on the surface of earth, and send one of them near a black hole that is at rest relative to earth, placing it there with its length alligned in the radial direction of the black hole, would I see the rod close to the black hole with a length shorter...

What would happen if a mechanical chopper choped a linearly polarized laser pulse with length of 1.125 cycle? (consider propagation from right to left)This would be feaseble with a mechanichal chopper. And it gives a non zero area EM fields. What would happen to the wave form far from the source?

So, a pulse length must be integers multiples of one wavelenght?

My knowledge about electromagnetic fields treatment is limited. But I understand that a circular polarized electromagnetic beam have rotating E and B fields with constant magnitude, therefore, give constant magnitude (and direction) for energy flux S. But for other cases (elliptical and...