Classical Physics

1. Is there an evidence for black holes 2. Is singularity possible? 3.If the Sun becomes a blackhole, will the planet's continue to revolve as if the Sun is still present?

I was just heating some frozen soup on my electric stove, and then remembered that supposedly as long as there is some ice left the system stays at 0°C until all the ice is melted, and only then does the temperature rise (if heat is continued to be added). I looked it up and this page (https://chem.libretexts.org/Courses/Valley_City_State_University/Chem_122/Chapter_2%3A_Phase_Equilibria/2.3%3A_Heating_Curves - sorry, couldn't find guidelines on how to properly post links) phrases it like this: "the temperature of a system does not change during a phase change. In this example, as long as even a tiny amount of ice is present, the temperature of the system remains at …

Newtons law of Cooling states that the rate at which an object changes temperature is directly related to difference between the temperature of the object and its respective surroundings and can be written in a differential equation as so: dT/dt = k(Tobject - Tsurroundings) The question I have is, in practical terms, what does the proportionality constant represent? specific heat?

If we feed two signals at 75dB Sound pressure level(SPL) and 120dB SPL into a microphone, what will be its output?Will the microphone takes both the signals or only the high powered signal(120dB SPL)

Hi, I would like to convert nM to PPB ( Parts per billion µg/L). Can you help me? I would like to covert the following concetrations measured in water samples from the North Sea: Ni = 3.66 nM Cu = 1.61 nM (Document: https://www.sciencedirect.com/science/article/pii/S0304420399000766?via%3Dihub )

So we are conducting a experiment with the Leidenfrost effect. We are trying to generate energy using this phenomenom. The leidenfrost effect occures whenever the temperature of the heated surface gets to around 210 degrees celsius. Reaching this exact temperature is important for the experiment. We thought about using a IR thermometer. But soon found out that because of the emissivity of Aluminium it wouldn't work. So we started to think about other ways to measure the temperature. We still haven't found a solution to this, but have come up to an idea. We thought painting the Aluminium Leidenfrost ring with some kind of black paint which an high conductance. What kind of…

The ubiquitous conventional graphic for a magnetic field through and around a cylindrical coil shows equidistant parallel lines through the central zone which it proclaims is a uniform magnetic field. We know that field strength fades proportionally to distance from a conductor therefore the graphic field lines should show this but they don’t. The field shown is partially uniform since the lines are parallel, but the force on a charge particle diagonally transversing a gap between two aligned opposite pole coils is initially zero, then rises in the middle, then falls back to zero as it approaches the other side. It is near hyperbolic. Science uses the same word…

Why is s ranging from r - R to r + R, can anyone show me me which distance is r -R and which one is r+R

Imagine two streams of identical charges moving (anti-parallel, parallel and opposite in direction) in a vacuum away from any opposite charges influence like as in wires etc. The two streams are close enough to each other that both the magnetic field and electric field are present. In their own frame of reference, there is an electric field of repulsion and a magnetic field of attraction between the streams to my knowledge. 1. Will the charges stay parallel? 2. Will they get close and closer until? 3. Will they be repelled more and more? 4. ? Thank you.

I have been confused about moving charges create circular magnetic fields around it. So if I have an electron moving into screen away from me, it will have a circular magnetic field that is clockwise. Another electron parallel to the above electron coming out of the screen towards me will have a circular magnetic field that is counterclockwise. So their magnetic field join instead of against each other. Do the charges repel as the consequence of their magnetic field joining? I assume the charges repel each other to my understanding. Which implies they prefer not have a joined magnetic field. What is missing in the picture that I have in my head…

A wire with resistance per unit length of 32.668 Ω/m is bent at a right angle. The second straight fragment of the same wire (The blue one) moves at the top of the first one at a speed of v = 4.2735 m/s. The whole system is located in a magnetic field with an induction of B = 8.4965 T, perpendicular to the wires (as in the picture). Determine the current flowing through the wires. Ignore the resistance at the points of contact of both wires and also the magnetic field generated by the current itself that is taken into consideration.

e are living in an accelerated world: have a look at the picture below We know that the distance between the poles is D. What appears to us is d4 larger than d3, larger than d2, larger than d1 etc If you are looking toward a motorcycle coming at you at constant velocity, what will you see? You will see the bike travelling d1 in say 1 sec, d2 in 1 sec, d3 in 1 sec, d4 in 1 sec. IOW you will see it coming slowly from far away, then progressively accelerating and suddenly wizzz in front of your eyes, then vanishing slowly to the horizon on the other direction. Like this: (link to a FB page with a Kawa at high speed) https://www.facebook.com/Kawasakiconta…

I have a couple of ideas and invention I developed over the years that I would like to patent. (One of them was the vaguely described idea for using undersea factories for global warming.) Could anybody explain the process to me? Also do add useful links in your answer if possible.

A small block was placed on a smooth inclined plane. The horizontal block distance from the lower end of the incline is b = 40.135 cm. The angle of inclination was adjusted so that the sliding time of the block was as short as possible, each time placing the block so that the distance b did not change. find the shortest possible sliding time T of the block. Assume that the acceleration due to gravity is g = 9.81 m /s2. Skip friction and air resistance. Any hints Highly appreciated. I just have a problem with correlating the distance b with the maximum angle possible to make the block even slide from the ramp.

Why atmospheric pressure measure at the bottom of this fluid because atm is exerted by atmosphere and the atmosphere is at the top of the fluid? I though atmospheric pressure should be measured at P0

Do we have the technology to transform mechanical energy, like that of a bouncing ball, into electricity? If so, would bouncing an incredibly large/dense “bouncy ball”, between two such surfaces, with a high initial rate of speed, in space, work to generate more energy than was used to start the ball movement. I figured the two “pads” for converting the energy would be across from each other within a ring, as to prevent a loss of the ball’s inertia when bouncing The ball would bounce between the two surfaces for an incredibly long time creating energy everytime it does so. I know its obviously not a perpetual motion machine for a number of reasons, but …

Hot air rises due largely to fewer molecules = lighter = rising. Cold air sinks since more molecules = heavier = sinking. Fine. But that regards the two conditions as separate instances. In reality hot and cold air are both present. My question: Isn't a certain amount of hot air 'pushed' up by sinking cold air? Mark

So I was wondering, and hoping maybe someone smarter than I could help me understand the specifics, the following: (and please correct me at any point if I'm wrong) The Law of Conservation of Energy implies that energy can't be created nor destroyed, and the energy taken out of a system can't exceed the work being put in. Thus, there must be work performed, you can't have a perpetual motion machine. Wouldn't this also imply that energy can't be created nor destroyed simply by the fact that there is always work being performed due to the transfer of energy? I only ask that because wouldn't that mean you can never truly have a "free" energy source? I …

Obviously S ≠ F in the below example due to efficiency loss in friction. How do I calculate the exact efficiency of this simple system? Lets say F=1kg, gravity is 1G, the rope is non elastic and the angles are straight like in the graphic. Lets assume the pulley and rope diameter to be some values which are easiest for calculations.

Hello all and thanks for viewing this, I am in need of some assistance to solve a problem to size an AC motor rotating this load (power transmission will be trough belt & pulley). I have a hollow cylinder (pipe) that needs to spin 25 RPM: - OD = 50 mm - ID = 48 mm - M = 200 kg - Total length = 40m The formula for inertia (Z-axis) i found when searching for a hollow cylinder = I = M * r^2 this gives me a solution of I = 0.1201 kg/m² If i put this in the torque formula of T = I x angular acceleration = 0.1201 kg/m² x 2.618 rad/s2 (25RPM - 1 sec - ) = 0,3144218 Nm? I'm stuck here :) would like to have some advice in where to search. Thanks so much for t…

Electron-Positron Annihilation, low energy vs high energy mode- do both end in 511 keV Annihilation? Normal room temperature electron-positron annihilation is a well documented process, used in industrial, medical and metroloogy fields, among others. There are two modes of e-p annihilation, the room temperature or so-called low energy model, and the high energy model (think storage Rings, accelerators, colliders). In the latter category, do the e-p particles annihilate and produce 511 keV opposed photons like in a normal annihilation, or is there a threshold where e=p annihilation can be forced by kinetic energy alone? Citations/ re…

First to say, how ridiculous that on scientific forum I am no see any things that can help me to type formulas... But instead of it a lot smiles. It is a very fun, but what about Latex or something? My second is connected on the first, I will try to formulate my questions in laconic way and without formulas: is wavelength changing when source of waves moving related to medium? The point is my 'plank-core' one-dimensional model (the ballistic one) is seems to say "yes it is", the wavelength changing, I have attached files that contain the picture that illustrating the rest and moving case of source, related to the medium. But the very Galilean transformation of the w…

Would it be possible to have some explanation about the dispersive and reactive medium in the field of mechanical waves. As far as I understand : Let w be the excitation frequency and w0 the natural frequency. - In dispersive medium : sine waves are spread and w > w0 - In reactive medium : exponential waves are spread and w < w0 However, how can you create them ? For instance, to create a reactive medium, you would add an excitation force (e.g. Fcos(wt)) at an extremity of the system that would be lower than the lowest mode ? So you would create a lower-pass filter ? I'm not sure to understand how you can create low-pass or high-pass filter. …

Why is the pressure on top of this fluid elements on the right equal to p+dp

Does the latter follow from the former? If two bodies are in the same inertial frame of reference and an attempt is made to make them move wrt each other by physical measures limited to those 2 bodies does it not follow that any increase in velocity multiplied by mass of one body must be counterbalanced an equivalent velocity multiplied by mass of the other body? Does this show that the increase in relative velocity cannot be linear and also that there must be a finite velocity for any two bodies which is a function of their combined masses? Looked at another way ,in the famous example of a moving passenger on a moving train as…