Recent content by jonander

Sorry, I don't understand what you mean with the "scale-up" In the lecture, he performs a scaling argument with femurs based on a Galileo's assumption. He makes several operations involving proportionality with the mass and lengths of the femurs. These kinds of analysis and the procedure are...

Hi Chester, thanks for replying. I know that in the lecture Walter performs a dimensional analysis, but that's after the scaling argument with the femur.

Hi everybody, After watching the first lecture by Walter Lewin from MIT, I'm finding hard to follow the part in what he talks about scaling arguments. I've been watching around the Internet for resources to get my head around it but I couldn't find much or maybe I'm not using the right...

The first Newton's law is defined in the same way both in Wikipedia and the textbook. After Russ saying that the definition of a perpetual machine doesn't necessarily involve "operating forever" I got surprised and I just looked straight on the Internet (and in this case, Wikipedia for the...

Absolutely not. I'm enrolled in a distance learning Physics degree. At the moment, I'm currently reading the "University Physics with Modern Physics" textbook.

Thanks for the clarification! Indeed, I think I have mixed the situation of a body in perpetual motion speaking only in the context of Newtonian mechanics with the full situation that brings up energy and thermodynamics arguments.

Thanks for you reply. I understand that it's a huge "if", therefore my hypotetical road just to see if I was missing something in the picture that needs to be completed with thermodynamics. You say that thermodynamics doesn't need to be involved. May I ask how does this situation differs from...

Hi! I knew about the "big bang" (neither big nor a bang) but it's the first time I heard this kind of definition. Do you more sources about it? Not the topic of perpetual motion, but your suggested definition. Wikipedia points to the popular one.

Hi everyone! I have started to study physics this month and I got to the Newton's laws. According to Wikipedia, the first law is: This definition made me wonder: If there was, let's say, a fictional road, infinite long and frictionless, and a body would move in constant velocity over it, could...

Sorry for the confusion guys. I saw that that answer was wrong, asked here for confirmation on my alternative, and, after that, I edited the answer in Stack Overflow. And, yes! Thankfully, answers in StackExchange can be improved/edited.

Oh, indeed, they are the same now. It seems that the edition request has been approved.

I'm saying that the author of this answer, got the equations in the wrong places. And what I wrote in my post is what it should be.

Hi Perok, thanks for replying. I tried already with a few cases and I'm kind of sure that the author got the equations reversed. I'm asking mostly for confirmation.

Thanks for the confirmation, phinds.

Hi everyone, While finding the solution for one of my exercises, I found the following answer. I'm seriously questioning if the equations provided in that answer are reversed. According to my understanding, if two vectors ##\vec{S}## and ##\vec{T}## are parallel (same direction) the magnitude...