Law Definition and 999 Threads

Law is a system of rules created and enforced through social or governmental institutions to regulate behavior, with its precise definition a matter of longstanding debate. It has been variously described as a science and the art of justice. State-enforced laws can be made by a group legislature or by a single legislator, resulting in statutes; by the executive through decrees and regulations; or established by judges through precedent, usually in common law jurisdictions. Private individuals may create legally binding contracts, including arbitration agreements that adopt alternative ways of resolving disputes to standard court litigation. The creation of laws themselves may be influenced by a constitution, written or tacit, and the rights encoded therein. The law shapes politics, economics, history and society in various ways and serves as a mediator of relations between people.
Legal systems vary between countries, with their differences analysed in comparative law. In civil law jurisdictions, a legislature or other central body codifies and consolidates the law. In common law systems, judges make binding case law through precedent, although on occasion this may be overturned by a higher court or the legislature. Historically, religious law influenced secular matters, and is still used in some religious communities. Sharia law based on Islamic principles is used as the primary legal system in several countries, including Iran and Saudi Arabia.Law's scope can be divided into two domains. Public law concerns government and society, including constitutional law, administrative law, and criminal law. Private law deals with legal disputes between individuals and/or organisations in areas such as contracts, property, torts/delicts and commercial law. This distinction is stronger in civil law countries, particularly those with a separate system of administrative courts; by contrast, the public-private law divide is less pronounced in common law jurisdictions.Law provides a source of scholarly inquiry into legal history, philosophy, economic analysis and sociology. Law also raises important and complex issues concerning equality, fairness, and justice.

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  1. R

    I Big Freeze and Law of convervation of energy

    (Kurzgesagt- In a Nutshell) says that in the Big Freeze scenario all the matter will decay in the end, how is this possible without breaking the law of convervation of energy?
  2. Arman777

    Gauss' Law: Charge distribution on concentric spherical surfaces

    Homework Statement A metallic sphere of radius a is placed concentrically with a metallic spherical shell with inner radius b and outer radius c. The sphere has a total charge of 2Q and the shell has a total charge of 3Q. (a) What is the charge distribution? Specifically, what is...
  3. A

    I Entanglement, magnetic field and conservation law

    I am not sure that I fully understand even the basic aspects of the Quantum measurement and entanglement but I just came across this thought experiment and I wish to resolve it. In a setting of two entangled spin-1/2 particles, suppose that Alice applies a uniform magnetic field ##B_0## along...
  4. Arman777

    Cylinder rod charge density (Gauss Law)

    Homework Statement Theres a cylinder rod inner radius a outer raidus b.we want to find electric field between a and b,like point r (or radius r) a<r<b. Homework Equations Gauss Law The Attempt at a Solution [/B]I am trying to find Q enclosed but something make me confused.I am...
  5. Arman777

    Uniform Slab-Finding Electric Field Using Gauss Law

    Homework Statement Uniform Slab: Consider an infinite slab of charge with thickness 2a. We choose the origin inside the slab at an equal distance from both faces (so that the faces of the slab are at z = +a and z = −a). The charge density ρ inside the slab is uniform (i.e., ρ =const). Consider a...
  6. P

    What is the value of I3 for the given line integral and values of I2 and B?

    Homework Statement The value of the line integral around the closed path in the figure is 1.79×10−5 Tm . https://session.masteringphysics.com/problemAsset/1385538/4/32-22.jpg There is I2 and I3 inside the closed loop. I2 = 12 A What is I3? Homework Equations Amphere's Law: B = Uo I(enclosed)...
  7. C

    Rate Constant Determination - Isolation Method Homework Help Needed

    Homework Statement Due to formatting problems, I have attached the problem below. Homework EquationsThe Attempt at a Solution Plotting the appropriate graphs and based on linearity, I have determined that the reaction is first order with respect to [O2] and second order with respect to [NO]...
  8. J

    Understanding the Different Forms of the Ideal Gas Law and Their Applications

    Hey I was hoping someone could be me a succinct method of knowing what form of the Ideal gas law I need to use and in particular the different R's associated with each form. Form my Thermodynamics class we use PV = nRT Pv = RT PV = mRT Little v being the specific volume (which changes the R...
  9. C

    Rate Law Problem 1 Help: Finding OCI- Concentration Effect

    1. Homework Statement Due to formatting problems, I have attached the question below. The attempt at the solution: I am not sure how to deal with the hydroxide ion since it is written above the arrow. I believe that this signifies a species not included in the overall reaction but is...
  10. aatari

    Newton's Second Law: Car and Rock Problem

    Hi Guys, I solved two questions below. Just need some feedback to make sure I solved them correctly. Thanks a bunch. 1. Homework Statement A car of mass 1.4 tonnes (1400 kg) traveling down the highway at 120 km/h has a F air of 1800 N acting against it. What force must be applied by the...
  11. Dileep Ramisetty

    I Is my approach for pascal's law wrong?

    In hydraulic lift utilising pascal law, larger piston area is A1 and the smaller piston area is A2 mass in = mass out and volume in = volume out (in-compressible),so A1*x1=A2*x2 (let x1 and x2 are displacements of respective pistons) A1*V1 =A2*V2 (on differentiation gives continuity...
  12. grandpa2390

    Gauss' Law -- Clarification about using the equation please

    Homework Statement I keep getting confused about this part of Gauss' law. Is the da on the left side the surface area of the the Gaussian surface? and on the right side when I am integrating. I say that q = the charge density multiplied by something. Is that something surface area of the...
  13. J

    Newton's Second Law -- Accelerations in a pulley system

    Homework Statement A 20-kg block with a pulley attached slides along a frictionless ledge. It is connected by a massless string to a 5.0-kg block via the arrangement shown in Figure. (a) draw complete free body diagrams for the masses and Find (b) the acceleration of each block and (c) the...
  14. aatari

    Newton's Second law: Tension on Cable

    Hey guys is my solution correct for the question below? 1. Homework Statement Consider a 5.0 kg watermelon that is being accelerated at 2.0 m/s2 [up] by a cable. Find the tension in the cable. Homework Equations Fcable = m.a The Attempt at a Solution Fcable = m.a = 5.0 kg(2.0) = 10N
  15. E

    Themodynamics: calculating the partial pressure with Dalton's Law

    Homework Statement In a sealed container is Helium ##M_{He} = \frac {4kg} {kmol} ## with a pressure of ## p_{He} = 4bar##. now is Methan put isothermic inside the container till both the methan and the helium mass are equal( ##M_{CH4} = \frac {16kg} {kmol} ## Calculate using the ideal gas law...
  16. aatari

    Newton's Second law: Pushing the box

    Can someone please help me solve this question below. 1. Homework Statement How much force is needed to push a 20 kg box across a floor at a constant speed of 0.5 m/s [forward] against a frictional resistance of 4 N? Homework Equations Fnet = m.a The Attempt at a Solution Since the velocity...
  17. P

    Efficiency and Law of conservation for a skateboarder in a skate park

    I have to design a track for a skate boarder that is 50% efficient (friction must be present) from the start of the skater's drop-in, to his furthest point along the track. My skater's mass will be 75kg efficiency=energy output/energy input x100% I am not really sure where to go next and how...
  18. Adam Bourque

    Affinity Law and Efficiency of a Pump Curve

    Homework Statement (Pump Curve given as attachment) [/B] Find the point where the pump is delivering 1,200 gpm at 45 ft of head. I. What is the pump efficiency (read from the pump curve data)? ii. What is the hp delivered to the water? iii. What is the shaft hp required to drive the pump...
  19. J

    Electron Scattering and Bragg's law

    Homework Statement A beam of thermal neutrons (K = 0.025 eV) scatters from a crystal with interatomic spacing 0.45 nm. What is the φ angle of the first order Bragg peak? (as defined in figure 5.11, φ and the scattering angle add up to 180 degrees). Homework Equations nλ = 2dsinθ = DsinΦ d...
  20. I'm Awesome

    Understanding Newton's 2nd Law

    I have a problem which reads: A frictionless pulley with zero mass is attached to the ceiling, in a gravity field of 9.81 m/s2 . Mass M2 = 0.10 kg is observed to be accelerating downward at 1.3 m/s2 and I have a solution which tells me to solve the problem use Newton's 2nd law: m1a1 = T1 -...
  21. B

    How low can I go with voltage to increase current in a resistive AC circuit?

    Simple premise: take ohms law with a purely resistive ac circuit. 1 volt through in series with a 2 ohm resistor, I have 0.5 amps of current. I want to maintain constant power. In practice, "how low can I go" with the voltage to increase the current? There's probably many variables I'm missing...
  22. M

    New Explanation to How Newton's Third Law is Satisfied in Magnetism

    <Moderators note. Moved from the quoted thread to avoid detracting> Newton third law does apply in magnetism, and this is proved by applying the conservation of momentum principle. This will be clearer when the causes/origin of the magnetic force is understood as described in the work "Two new...
  23. G

    Is there microscopic version of general Ohm's law of V=IZ?

    Hello. Resistive Ohm's law is famously known as V = IR. We can derive its microscopic version as being followed. V = El, where E and l are, respectively, an electric field and a resistive load length over which a voltage drop V is developed. I = JS, J and S are a current density and a...
  24. G

    Ballistic Lenz's Law: Magnet Induced Current in Copper Tube

    If a magnet was going fast enough as it approached/entered a copper tube, could the current induced in the tube via Lenz's Law be high enough to melt or even vaporize the tube?
  25. I

    Hess's Law Explained | Simple Explanation for Enthalpy Change

    Homework Statement I need to research Hess' law, but I can't find a simple explanation. I know that the enthalpy change between the reactants and products is the same as the enthalpy change between the reactants and something else, and between that something else and the products, but I don't...
  26. tze liu

    A Newton's law question which is too hard for me

    Homework Statement Question 1. A triangular prism of mass M is placed one side on a frictionless horizontal plane as shown in Fig. 1. The other two sides are inclined with respect to the plane at angles a1 and a2 respectively. Two blocks of masses m1 and m2, connected by an...
  27. G

    Some confusion of Faraday's law of induction.

    Hello. I have several confusions regarding Faraday's law of induction. EMF = \int_{}^{} {\vec E \cdot d\vec l} = - \frac{{d\Phi }}{{dt}} = - \frac{d}{{dt}}\int_{}^{} {\vec B \cdot d\vec S} . It means that If the magnetic flux Φ through the closed conducting loop changes in time, electric...
  28. D

    I Lambert's Law differential equation

    22. According to Lambert's law of absorption, the percentage of incident light absorbed by a thin layer of translucent material is proportional to the thickness of the layer. If sunlight falling vertically on ocean water is reduced to one-half its initial intensity at a depth of 10 feet, at...
  29. Drakkith

    Newton's Law of Cooling When the Temperature of the Air Isn't Given

    Homework Statement You come across a dead body at 3 PM. Its temperature is 83.6 F. 30 minutes later its temperature is 78.6 F. How long was the guy dead before you found him? Homework Equations ##\frac{dT}{dt}=-k(T-Tair)## T(0) = 83.6 F T(0.5) = 78.6 F The Attempt at a Solution This is a...
  30. G

    Transformer equation: Using Faraday's law "the wrong way"?

    Hi. All derivations of the (ideal) transformer equation ##\frac{U_p}{U_s}=\frac{n_p}{n_s}## use Faraday's law of induction $$U=-n\cdot \frac{d\Phi}{dt}$$ for primary and secondary and equate the change of flux ##\frac{d\Phi}{dt}##. Until now, in my textbooks it was always like this: Electrical...
  31. HethensEnd25

    Rearrangement of the First Law of Thermodynamics

    For class we have been asked to show how the first law of thermodynamics dU=dQ+dW can be shown to be dQ=(CV/R)*VdP +(Cp/R)*PdV I have an answer, but am hesitant to say it is a final answer. I will admit that while doing the problem I had trouble following what I was doing. Hence my...
  32. Tobi

    Faraday's law or Lorenzt force?

    A student in my physics class posted, in a group, a wrong answer to a question. The situation was: A plane has a wire extended between the tips of its wings and flies through a magnetic field, perpendicularly, while accelerating. The question was: What will be the induced current? His answer...
  33. T

    I Hubble's Law, Friedman Models & Spacetime Curvature Explained

    Is the Hubble's law(recessional velocity linearly proportional to distance) valid for all cases even when the spacetime is curved? Is there a nonlinear model for Friedman models or it's always linearly proportional?
  34. I

    Newton's 2nd Law Problem, Angle exerted on block by surface

    Homework Statement Problem: A 12.0-kg block is pushed to the left across a rough horizontal surface by a force that is angled 30.0◦ below the horizontal. The magnitude of the force is 75.0 N and the acceleration of the block as it is pushed is 3.20 m/s^2 . What angle does the force exerted on...
  35. S

    Solving Faraday's Law Problem: Finding EMF Needed to Stop Current at Middle R

    Homework Statement If I have the circuit below, and the white circle is Infinite Coil with current of I=xt, Counterclockwise, with a radius a. from Faraday's law we know that will be Electromotive force . 2. Homework Equations what the EMF in needed to stop the current at the middle R ? The...
  36. J

    Charge on a cavity wall and Gauss' law

    Homework Statement An isolated conductor has a net charge of +14.0 × 10- 6 C and a cavity with a particle of charge q = +4.30 × 10-6 C. What is the charge (a) on the cavity wall and (b) on the outer surface? Homework EquationsThe Attempt at a Solution So I understand that B is just adding the...
  37. I

    Revisiting Newton's Second Law

    I wonder why Newton second law, define force as mass x acceleration, acceleration is the second time derivative of displacement, why he didn't define the force as mass x higher order time derivatives of displacement
  38. Eri ep

    I Differentiating Biot-Savart Law

    Hello! I have the equation FM = qvBsinθ . As the end result, I am trying to figure out what B I need to change θ even a little bit. To do that, I was planning to find the minimum B by differentiating B=(μe/4π)(qv x R / R3) in terms of R and setting it equal to zero. . I am assuming that this...
  39. D

    Coulomb's law; vector form problem

    Homework Statement 3 charges are placed like shown: Q1 __4cm____ Q2 ______6cm___________Q3 Q1=-2nC Q2= 1nC Q3= 3nC Find the resultant force and its direction upon the charge Q3. Homework Equations F=k0*(Q1Q2)/r2 k0-constant, equals to 9*10^9 r-distance The Attempt at a Solution...
  40. E

    Contradiction with Kirchhoff's Radiation Law?

    Hello everyone, I am working on understanding how Kirchhoff's Radiation Law applies in the real world. Basically, the absorbed solar radiation must equal the thermal radiation if a surface is to be at equilibrium. Certain relationships follow from this assumption, namely, for an opaque...
  41. A

    B How to find the appropriate area in Gauss' law

    Knowing that Gauss' law states that the closed integral of e * dA = q(enclosed)/e naut, how would you find exactly what A is in any given problem? I know it varies from situation to situation depending on the geometry of the charge. For instance, I know that for an infinite wire/line of...
  42. L

    Coulomb's Law problem: Charged particles and the net electric field and force

    Homework Statement Figure (a) shows charged particles 1 and 2 that are fixed in place on an x axis. Particle 1 has a charge with a magnitude of |q1| = 19e. Particle 3 of charge q3 = +16e is initially on the x axis near particle 2.Then particle 3 is gradually moved in the positive direction of...
  43. S

    Diffraction grating problem involving Snell's Law

    Homework Statement A 600 line/mm diffraction grating is in an empty aquarium tank. The index of refraction of the glass walls is [n][/glass] = 1.50. A helium-neon laser (lambda=633 nm) is outside the aquarium. The laser beam passes through the glass wall and illuminates the diffraction grating...
  44. harini07

    Hooke's law and wave velocity related problem

    Homework Statement The extension in a string, obeying hooke’s law is Y when wave velocity in it is V. if extension is increased to 1.5Y, then wave velocity V’ becomes? 1) V' =V. 2)V'= 1.22V . 3)V'=1.5V. 4) V'=0.75V. Homework Equations wave velocity= frequency*wave length. The Attempt at a...
  45. J

    Calculating Electric Field Using Coulomb's Law

    Homework Statement Homework Equations Ex=1/k*1/(a^2/2)*1/(sqrt2)*cos(theta)*(sum of charges) Ey=1/k*1/(a^2/2)*1/(sqrt2)*sin(theta)*(sum of charges) The Attempt at a Solution So first off I can see that I don't need to calculate the force in the x direction as each q cancels out when...
  46. R

    Need help on Newton's Law Question and Determining speed

    <Mentor's note: moved from a technical forum, therefore no template> My teacher made this question: Iceman is sliding down a 10.0 x 10^(-8) nm ice that is inclined at 20.0 degrees with respect to the horizontal. Iceman is initially at rest. The coefficient of kinetic friction between iceman's...
  47. G

    Faraday's law for constant velocity, area and B-field

    Hi. If a planar wire loop is moved through a homogeneous magnetic field (field lines perpendicular to the loop plane) with constant velocity and no rotation, Lorentz force will move some electrons to one side of the loop, creating a potential difference. But how does this work with Faraday's...
  48. mr_persistance

    State the trichotomy law formally

    1. For arbitrary real numbers a & b, exactly one of the three relations hold: a < b, a > b, a = b. How do I state this more formally while also being correct?2. The attempt at a solution a, b ∈ ℝ ( (a < b) ⊕ ( a > b ) ⊕ ( a = b) ) From this I made a truth table 2^3 entries long, and what we...
  49. J

    I Explanation of Biot-Savart Law

    I've learned that in a wire with a current flowing through it, a magnetic field is produced, and that to determine the direction of the fields, one could match their thumb with the direction of current and curl their fingers around the wire as shown in the link below. I also learned that in Biot...
  50. A

    Possible variables for Coulombs Law?

    COULOMBS LAW F= K Q1 Q2 / R2 How would I solve for Q1 and Q2?
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