Recent content by DrewD

It sounds like the question has been mostly answered, but I don't see a direct answer to this, so I will try to clarify. A light like ds is a space-time interval. This is invariant for all inertial FoR. I can measure the ds between light being emitted and then absorbed somewhere else from my...

I think it is important to note that you could be asking two very different questions: 1) According to current theories, what is the size of fundamental particles? 2) If we consider the experimental upper bounds, what is the smallest particle measured? It seems like your question is 1), but...

Force is the rate of change of momentum with respect to time. If the object stops instantly, you are going to have some problems.

Yes, it was luck. I didn't mean to encourage people to guarantee good values with only a few hundred points.

I should correct my earlier comment: I meant that I often have accurate answers. I usually only do this experiment in classes that are not advanced enough to understand variance and estimating errors. Most of the time we have gotten decently good values with about 200-500 points per class.

I do this with my students for a fun activity every year. With enough drops you can easily get three of four decimals correct. What is your trick for improving precision?

You are not alone in this thought, but you are not correct. The problem in your intuition is that the entangled particles are not separately in fixed states that change. They are in a shared state and you cannot control which one ends up in which outcome. It is only guaranteed that they will be...

As everyone else has said, the answer is no. You could only draw the conclusion you draw if the objects are the same (same mass and distribution of mass). To be more precise, the moment of inertia needs to be the same. I think you could draw this conclusion from other posts, but I just wanted to...

Khashishi answered for permanent magnets. For an electromagnet, there will be no closed electric field lines outside of the wire coils. It is essentially the same if you are viewing it completely outside of the material. Remember, electric current is a flow of electric charges, but the net...

I think Nugatory is saying that a good answer to a "why" question depends on the person asking the question. Perhaps the system dropping to a more stable equilibrium is a good answer. Perhaps because of QED is a good answer. Maybe that's not enough and someday strings or another theory will take...

I'll try to find one, but as I said, I only recall a professor telling me this. I may have just misunderstood what he was saying.

Don't be. Since this is Physics Forums and you are posting in the general physics sub, it should be abundantly clear what this formula is despite the fact that you didn't explicitly define the terms. You are asking for a clarification about the formula ##F=-\frac{dU}{dx}## where ##F## is force...

It might be useful to think about the definition of the summation function as ##\sum_{n=0}^Nf(n)=f(0)+f(1)+f(2)+\ldots+f(N)##. Then ##f(n)=1## for your example and the definition works. Usually this is written with ##f(n)=a_n##, but for some reason when I saw it with ##f(n)## for the first time...

It doesn't mean that we only hear the fundamental, but we perceive the note as the fundamental. You hear all of the other frequencies, but they are perceived as timbre or color. If you strike a guitar string, it vibrates at ##f_1## and many (many) other frequencies. Certain higher frequencies...

I only posted the part that you could guess. If you check on the wiki page you can find the pertinent integral that will give a better understanding.