Classical Physics

What is the difference between weak and strong laws of action and reaction? Can you give any examples?

Hi everyone! Today I was watching a performance by Tokyo Philharmonic Orchestra at NHK Symphony Concert Hall building and got this question. As you can see in the image below the concert hall looks pretty fantastic and what you can notice straight away almost everything is either wooden or covered with wood. I sort of understand the idea behind this: since for many if not most of orchestral instruments sound is created amplified within a wooden chamber, if afterwards it is reflected by a non-wooden surface if may change its characteristics somewhat compared to the original. Hence in order to preserve the proper sound its wood all around. But anyway, does this hav…

I was re-watching Interstellar last week (my wife hasn't seen it before) and had a question about yet another physics inaccuracy in the movie... or so it seems to me. In the end in order for Dr. Amelia Brand to get to the last planet in the system they haven't visited yet her and Coop fly Endurance and perform a powered gravity assist using central black hole for that purpose. First issue is that you can't use central body of the system containing pretty much all the mass as a gravity assist, because in that stellar system FoR is would have zero momentum and hence you can't get any out of it. Although they did briefly mention a neutron star in the same system, so…

EM Spectrum Questions from a lay-person: What are the upper and lower limits of the spectrum? I mean the uppermost- and lowermost-possible wavelengths. Also, what defines the endpoints of the spectrum? There must be some law/relationship between wavelength and energy that constrains the EM spectrum to upper and lower bounds. Diagrammes of the spectrum show it as a continuum; are gamma rays really the same as radio waves, just shorter wavelength/higher energy photons? As I said, I am just a lay-person trying to learn. Please try to keep your answer simple (if possible). TY!

I have a small room. 6m by 5m. I want to get it carpeted so I compute its area. Area= 6m × 5m = 30m2 ( metre square). But.... Muliplication is also repeated addition.. so, I add 6m + 6m + 6m + 6m + 6m..... but I get the answer 30m and not 30m2. My point is... Irrespective of how we do multiplication the answer (including the units) should be same.... but by repeated addition I get the same numerical value but not the same units. 1. Either mathematics does not depict nature/reality properly. Or 2. I am insane.

What would the mass be of a spaceship weighing 100 tons and be moving at 10% the speed of light , and will it be enough to bend spacetime or gravity. And increase its speed further like warping almost

So I've been thinking about an idea for a motor that doesn't really need fuel. Perpetual motion machines have really gotten my mind wrapped up in a knot and i have an idea I'd like to talk to someone about.

What will happen to our universe if Newton's third law did not exist? I know this sounds like a stupid question, but I'm just being curious.

Hello, Given that distance is path-dependent and displacement measures only the net change, how do we define speed? I have seen speed defined as 1) distance over time, and 2) the magnitude of velocity. I recognize that these are two different things because distance is path-dependent while velocity = displacement/time and displacement measures net change. Thus, which definition is the accepted definition for speed?

Imagine a very basic DC circuit consisting of a battery, a bulb, and 2 wires connecting them. The wires are each 1 light year long (yes, a huge circuit). You connect everything together, then attach the battery... How long would it take for the light to illuminate (ignoring wire resistance, battery capacity, etc)? 1 year for the electricity to get to the bulb, or 2 years for the circuit to be completed? Depending on the reply I have follow up questions. Thanks!

I saw a great video on YouTube on magnetic levitation. The spinner remains suspended in the air above the magnet. If the earth is rotating at 460 m/s why doesn't the spinner fall to the ground? Surely the magnet would move away due to the rotation of the earth, thus the spinner would eventually fall. As far as I can tell there is only gravity and the magnetic force acting on the spinner no lateral forces.

Dear All, I created a system as the pic showing as below: 1. 6 x 9-V batteries in series (54V) 2. 2 x capacitors (0.1 uF, 63V) 3. 2 x activated carbon cotton board electrodes (distance between the electrodes is 1 cm) 4. The solution is water with 1.3% table salt After connecting all wires, i put the electrodes in the solution, and hope the ions attached onto the electrodes, After 1 hour, I took the electrodes out of the solution, but I found the concentration of salt was still 1.3%. Please tell me what thing I did wrong. THX

Hi all, its my first post & I'm glad to be here. I can't wait to contribute to the forum where I can. I wanted to ask first about electrical wiring, particularly stranded vs. solid core wire. What are the advantages of stranded over solid core wire other than flexibility? Do the numerous stands of wire offer some advantage? Also, what is it about some car alternators that they can offer more amperage over units of the same size? I can understand better rectifiers and voltage regulations can be used, but is it to do with the wire gauge sizes/turns ratio in the unit?

Lets consider a line of length 1m. If space is continuous, it means there is an infinity of points in this line. Now, size of each point=1/infinity=0 This implies that our line is of zero size because its constituents are all of zero size. How to resolve this contradiction?

Newton's second law states (roughly), The rate of change of momentum of a body is equal to the force acting on the body and is in the same direction.... Why 'equal to' and not 'proportional to' In various other formulas we use 'proportional to' and not 'equal to'. What's the difference?

F=ma, If I put a=1m/s2, F=m Does it mean that when an object moves with an acceleration of 1m/s2, it's force becomes equals to its mass? ( sounds utterly absurd, how can force become equal to mass, when they are completely different entities/concepts. It is like saying mango has become equal to a shoe...)

This is a silly thing, but something I've often wondered about. Please forgive me if I've posted it in the wrong place. The experiment would go like this- Take 4 equal measures of water 2 at 100 degrees c (or 99 degrees to still be liquid) 2 at 0 degrees c (or 1 degree to still be liquid) Put 1 hot into 1 cold measure, and 1 cold into 1 hot measure of water, at the same time, all at once, and then repeat the experiment slowly so that you can observe the temperature change over time to see if that would make a difference. Would both of these, now double measures of water, reach 50 degrees at the same time? In other words, can you heat something up, …

I practice kenpo karate, and in our technqiues for punching, we are told to deliver a punch but then as soon as it hits the target, recoil it back to yourself as fast as possible. I've tested this out numerous times on a punching bag (hi-tech right?), and every time I throw a punch and then recoil it, I move the punching bag further than just throwing a one direction punch. -Just curious ~EE

Gravity is higher on a object with a bigger mass and attracts smaller objects to it. But I have a theory. I will use this picture as an asset. What if m2 has a bigger density but is much smaller than m1, which is larger and is not extremely dense as m2. Would the gravitational pull be higher on m2 or would m1 still have more gravitational pull than m2? IAstroVIz

I realise I don't fully understand friction. All things regarding friction discussion welcome here please. Take a mass on a sloped table the friction holds it there. Apply a force from the side and increase the force till it moves. What direction will it move? Will it always move in the direction of the net force? Not just the direction of the force overcoming the friction. Are the forces of friction always present or do they build up to resist a push?

It seems to me that a geodesic is no more than an observed path, perhaps a predictable path that is dependent on interacting forces. Yet the tendency it seems is to relate the geodesic to warped space. This would seem to imply some type of energy to space. Rather than define a geodesic as a curved path the tendency is to define it as the straightest possible path. Again relating some type of energy that provides density to space that prevents any other possible path. Yet, it seems to me the in order to predict an objects path the only considerations needed are the forces and the mechanics of those forces observed. The path is a result and is not a sign of…

Can someone setting a friendly argument? The conservation of angular momentum says the angular momentum of a system before must equal the angular momentum after. That is Lbefore = Lafter So, if a runner has linear momentum just before they jump onto a rotating circular platform does this have to be taken into account when calculating the Lbefore ? One argument is that the Lbefore only comprises the rotating circular platform because the runner who only has linear momentum hasn't landed on the platform and the Lafter should include the runners angular momentum using their l converted linear speed to angular speed and their Moment of Inertia at the edge of …

Can gravitational constant point that the overall energy and mass of the Universe increase?

I placed glass jar on a playground merry go round which had a very shiny plastic surface. There was minimal friction. If it was placed near the edge it didn't take much angular speed to make it slide off and the initial sliding motion was radial but the further out it went the more it slid backwards to the direction of spin. If I started it off close in it needed a much higher angular velocity to get it started and the degree of swing to a transverse direction was much more accentuated. I understand this to be due to the very low friction meaning it was unable to accelerate to the linear velocity of the surface at the ever increasing radius. When it fell off it was…

Under the delicate evolution of the Universe I mean an information based evolution where information is the first appeared "physical entity" in proportion to nothing, which have determined the evolution of space(time) and the appearance of energy in proportion to the evolving space. Information is evolving with the Universe. (in other words: there is no all mighty God who created everything to be just there, which started to evolve and reorganize from itself - big bang theory?)