Classical Physics

I have a question. Before I start, I want to say that I know negative mass itself has not been observed or proven to exist, if it does at all. That is why this is more of a what-if question if that is okay. Anyway... Say an object has negative mass and therefore negative inertia. Now, considering inertial reference frames, or fictitious forces, objects with normal mass appear to move, such as going backwards seemingly when say, a car it is in speeds up. If a negative mass object were to exist, and were place inside the car before it speeds up, would the object appear to go the opposite direction of what a normal mass object would do when that car moves, as in that ne…

Guys, why in physics does the work done by the system have the POSITIVE sign, but in chemistry does the work done by the system have the NEGATIVE sign?

Hello guys, sound power level or sound pressure level are basically defined as logarithm of a ratio of the root mean square ("effective") pressure and reference pressure. In case of sound pressure level, the reference pressure was selected as 20 microPa since it is considered as threshold of human ear. The issue is the root mean square pressure - a harmonic signal is assumed in fact. This definition, in other words, is based on the idea that human ear hears something because of oscillations of the pressure in otherwise stagnant fluid having a constant pressure (e.g. atmospheric pressure). However, let us regard the following situation: A pressure probe is placed…

I am looking for decent physics books that would only include physics calculations and how to complete them. I couldn't find it anywhere so maybe someone could suggest a textbook/book

Now, if I am not mistaken, from what I know, the axis of rotation of a body usually goes through the center of gravity of a body. Also, the position of the center of gravity, if I recall correctly, does change when the position of the body of the living being or object in question changes. Well, just to make sure, I must ask: would the location of the axis of rotation change if the position of the center of gravity changes as well?

Consider this a laser beam fired between points A and B. Consider an infinite -1 observers, viewing the laser beam from all angles above below, sideways etc etc. Each observer receives photons onto their retina from the laser beam. So the light just doesn’t travel in a straight line but is seen by all observers at every angles. Does this mean that an infinite-1 number of photons travel in every direction to make the beam visible???????

I wanted to make sure of something here. Now, I believe it is the case when an object with lighter mass, or inertia, will travel faster and farther than one with a heavier mass or inertia under the same force. Now, consider an object that is light and one that is heavy, both going at the same acceleration, but with different forces acting, and they start moving across either the ground or the air, depending on where they are when a force acts on them. Now, with the same acceleration, which object will go farther before stopping, with either friction, air resistance, or a force exerted by something or someone that is the same force for both objects?

Why does the equation τ = -n.R.T.ln⁡ (v_2 / v_1) only work for reversible processes?

We all know this classic equation Work=-pressure external*delta volume and Pressure*Volume=#molecules*R(constant)*Temperature Can I rework the equation to be Work=-pressure (external)*delta (#molecules*R(constant)*Temperature/Pressure)

Hello Dear Scientists, I kindly ask for your patience with me as Im no scientist, but I'm learning. I have a few questions here. Today I came across this video on the BBC: http://www.bbc.com/earth/story/20161021-why-there-could-be-many-copies-of-you The scientist in this documentary says that the cosmos is eternal. But it cannot be according to basic scientific theory and understanding: a) Matter cannot be created. It is finite. Do we agree on this, or have I misunderstood the 1st law of Conservation of matter: According to the law of conservation of matter, matter is neither created nor destroyed, so we must have the same number …

i cannot transmit charge from foil1 to foil2 , there is loss.

So recently we covered the properties of momentum and linear collisions between rigid bodies. Now either they bounce off one another or move in the same direction but create no rotational motion. Im interested in finding a way to explain how a collision could create rotational motion, specifically between two round magnets traveling past each other. I tried doing this with some magnets i have at home throwing that at each-other. This creates a fast spinning motion where they are joined together. Can i use the conservation of momentum to help me figure this out?

I can't believe stars are other suns because I have seen a star stop shining in front of my eyes.

i was practicing on my electric guitar and i wanted to find something on my phone. so while resting my arm on the strings of the guitar i placed my thumb on the home button (i have an iphone 7, which uses the fingerprint sensor home button which is a sapphire crystal and uses a complimentary metal oxide semiconductor capacitive touch sensor to detect the fingerprints electrical charge or something right? ) and it gave my arm a very small electric shock! the amp also gives feedback whenever i place my thumb on the home button as well however, it seems this only happens when my phone is charging! i think i might have some idea of what’s going on here... but i’…

If I understand how induction motor works is that in a single phase induction motor there are no rotating magnetic field. Of course the rotor rotates just fine if not as good or efficiently as the three phase motor. My main point here is that the rotor does not need to follow a single rotating field for it to rotate, it simply follows the fields on the coils of the stator which is basically hardly more than a pair. So my question is really this. Lets indulge in a thought experiment and assume that a rotating magnetic field in a 3 phase induction motor is just a misnomer. All we have is the three pair of coils and their localized alternating field.. How would th…

let's say we have an electric car. the electric motor turns the wheels. there is a torque. torque is force times lever arm. is the distance from the center of the wheel to the edge of the wheel, the lever arm? if not, then where is the lever arm?

Is there a difference between electrical susceptibility and magnetic susceptibility or they are the same thing? if they are different what are the basic definitions for these terms (no mathematics included)?

Hi guys For a case presentation in neurosurgery, I'm talking about the Jannetta procedure, in which, in patients with a neurovascular conflict between a cranial nerve and an offending vessel (mostly an artery compressing the nerve and pulsating against it), a sponge-like matter (Teflon, Merocel ...) is surgically inserted between the nerve and the vessel. I'd like to briefly talk about how the sponge absorbs most of the pulsatile energy/impact of the vessel, preventing energetic transmission to the nerve. I can't seem to find, however, a physics model explaining this. Does someone have a good explanation on how sponge-like matters absorb kinetic energy and …

Let say we have a ferroelectric capacitor which is capable to store 1 joule of energy. Then we remove charged plates and remain only fully polarized ferroelectric. Are there some ferroelectrics which are capable to retain its polarization for a long period of time? If yes, then are they capable to store energy just in polarization (without plates or free electrons)? Could there be some significant potential energy change when ferroelectric polarizes? If yes, how much? Will it release some energy (for example in the form of heat) when it depolarizes for some reason? If a capacitor with plates is capable to store 1 joule of energy then how much energy the same polarized fer…

What dependency exist between electron beam density and speed of electrons in this beam? What methods could allow to increase beam density quite a much without increasing the speed of electrons?

Hi guys, I have this question about energy that I sometimes think about and I thought a good way to get some sort of answer is to visit a forum dedicated to science so here I am. My question might sound a little daft so here it is. I'm probably alone in thinking this haha! What happens to sound energy? They say energy can't be destroyed and can only change from 1 form to another.... like a light bulb changes electrical energy into heat etc. However, what happens if we listen to music? To my way of thinking our stereo system converts electrical energy to sound (and a bit of heat) but where does the sound energy go after the song is finished? does it just exist somewh…

Thanks for all your really informative answers to does light accelerate I have another more interesting question. For this consider the following crude analogy: Consider a perfectly spherical pin cushion about the size of a golf ball, it filled full of pins tightly packed together so much so that you can no longer see the pin cushion only the pins. Imagine this perfectly spherical pin cushion is suspended in the centre of a balloon , which itself is suspended inside a spherical hot air balloon, which is suspended is a sphere the size of the moon, which is suspended inside a sphere the size or earth , next the size of sun. Now extrapolate the pin lines outward until t…

Consider a photon emitted by a photon emitter, it travels through a vacuum and then into a block of glass, it travels slower through this than the vacuum right? It leaves the block of glass and continues through the vacuum until it hits its target. Q1. When it leaves the block of light where does it get the energy to accelerate? Q2. Where does it accelerate? If it does not how can it go from one speed to another without doing so? Q3. What is it's speed when it is halfway out of the block of glass? Q4. Consider a beam of light as a wave instead of a photon, same questions.

Hello, I just had a few questions about a black light that I bought: https://www.lowes.com/pd/Scorpion-Master-Mini-Flashlight-LED-Miniature-Flashlight-Battery-Included/3182999. It actually has a peak wavelength of 390 nm, and I was wondering if this thing had any chance of fading color off of shirts made from natural fibers (cotton, wool, etc.). I understand that the type of dye that was used is also important, but I do not know. 2.) If it does have that ability, I was wondering if anyone could explain why and how this particular flashlight has that capability. 3.) Is HDPE naturally resistant to this type of UV? Thank you and I look forward to your res…

If I took a magnet into deep space say outside our solar system where would the north seeking pole point?? 2. If I chopped it in half (in space) would I still get two magnets? 3. Thought experiment: if I had a very microscopic bar made of just two iron atoms, on earth, and I magnetised it whilst it was lying west-east what would make one atoms north seeking? If that makes sense??