# law

1. ### Newton law

I have a question and I need help. It is as follows: A long rope of 15 meters hangs on a tree. A 50 kg mass can hang on the rope; any additional mass will cause the rope to break. How long will it take you to pull a 30 kg mass box up the tree. What formula can be used to calculate this?
2. ### Fick's law

I have a sealed container which will be stored in a humid environment. The container has a small lid, which is opened briefly once a day. I would like to calculate how much water vapour will enter my container through the following transfer mechanisms; 1) Permeation of water vapour through the...
3. ### Plank law

Dear All, After understood the Rayleigh-Jeans law and the UV catastrophe I move now to Planck law. Regards Philippe
4. ### Rayleigh-Jeans law

Good Afternoon, As I told you in my presentation, at 70 years old, I start to learn physics. My brain is a little bit slow and confused…so sorry for my (most of prabable) trivial question. I read on a website that the law of Rayleigh-Jeans is given for the radiance function of wavelenght...
5. ### Ohms law

Ok, i have a question. I have a 3d printer that is 110 volt from wall to the power supply. The heated bed is 24 volts. I would like to know how much current is going to the bed of a 12volt heated bed vs a 24 volt bed. I do not use ohms law offten, but is it power/voltage equals current? Or is...
6. ### First Law of Thermodynamics

I read from a famous text-book : "when mechanical work is done on a system of gas, the internal energy of the system increases." According to the formula of the First Law of Thermodynamics,it sounds true. But ,theoretically, when we do work on a gas , it compresses,i.e.,its volume...
7. ### Inverse square law?

If the volume of a sphere increases as the cube of the radius, and light propagates as a sphere, why does the intensity of light decrease as the square of the radius, rather than as the cube?
8. ### First law over constricting pipe section

So i am trying to get a sense of the change in internal energy for a fluid that flows through a constricting pipe (d_{out}<d_{in}). Bernouilli won't do since the flow is turbulent, hence it contains irreversibilities which will affect the internal energy. First law: U_{in} +...
9. ### Slight misunderstanding with a coulombs law question

Hi there, The question reads as: Two point charges +q_{1} and +q_{2} are positioned at (-a,0) and (+a,0). If +q_{1}=+q and +q_{2}=+3q, determine the position on the x-axis where the electric fields \underline{E_{1}} and \underline{E_{2}} are equal and opposite. The way I tackled this...
10. ### Zeroth law and Mathematics

so i have a question. zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other. in mathematics its defined that if a=b and b=c then a=c. its same as the zeroth law. which was...
11. ### Does Light obey Newtons First Law?

We know that Light travels slower in mediums other than vacuum. Scientists were able to drag light to the speed of sound. We know that drag is a force. So is it not drag that slows the speed of light in a fluid? https://phys.org/news/2011-07-scientists.html Newtons First Law states: An object...
12. ### Gauss's Law question

On the subject of solid conductors having zero electric field internally ... I feel as though I understand how any additional charge inside a conductor would repel itself to the surface, and that the temporary existence of electric field internally would result in charge moving in a...
13. ### Hook's Law Graph Orientation

Hook's law is commonly represented with F along the vertical Y axis and extension along the horizontal. This is what the text books stipulate, at l;east in the UK. I've seen an Asian video which has it the other way around, but elsewhere it's as stated. Yet this commonly-accepted orientation...
14. ### Lenz's law - mathematical model of experiment

Hi, I need help with writing mathematical model of experiment that demonstarate Lenz-s law (the magnet trough copper tube). N7tIi71-AjA I want to write the model and simulate it in matlab/simulink. On the following link https://brilliant.org/wiki/lenzs-law/ there are a mathematical...
15. ### Newtons second law for the layman.

Newtons all three laws are valid only in an inertial frame of reference. Here we look at newtons second law. But first, we define inertial frame of reference: An inertial reference frame is one in which a body at rest stays at rest and a body in motion continues to move at a constant...
16. ### Hooke's Law Spring Calc

Hello Members, It's a pleasure to join your forum. I have a spring calc I'd like to present for consideration. Load on Springs: 242.25 MT (each cycle) Load Axis: linear, horizontal Number of Springs: 2 Spring.A Position: left end of linear shaft Spring.B Position: right end of...
17. ### Jigsaw puzzle and second law of thermodynamics.

I have read that when you decrease entropy somewhere it has to increase elsewhere. So when you put a jigsaw puzzle in order this decreases entropy of the puzzle but it should increase entropy elsewhere but where? When you decrease the entropy of a system it should increase elsewhere but where...
18. ### snell's law and variational calculus

Working through some exercises on Variational Calculus from Taylor's Classical Mechanics. I'm not entirely sure how to set this up. I had a look at past post "http://physicshelpforum.com/advanced-optics/10876-does-fermat-principle-explain-refraction-inside-water.html" but the problem...
19. ### Earths angular momentum and newtons second law.

Newtons second law states: A force applied to an object changes its state of motion. If the object is at rest, it will start moving. If it is moving, it will speed up, slow down, or change direction. The change in motion depends on the mass of the object. Can we interpret this way? The earth...
20. ### Gauss's Law for an offset (non-origin) charge.

Can anyone see where I have gone wrong here? This is just a problem I made up for myself and I almost got it to come out but not quite. According to Gauss's Law I should get \frac{Q}{\epsilon_0} but it doesn't quite come out. I have a charge q offset a distance a_x along the x...