Laws

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Newton's First Law: 1. (Law of inertia): A body at rest remains at rest and a body in motion continues to move at a constant velocity unless acted upon by an external force.
Newton's Second Law: 2. A force F acting on a body gives it an acceleration a which is in the direction of the force and has magnitude inversely proportional to the mass m of the body: F=ma
Newton's Third Law: 3. Whenever a body exerts a force on another body, the latter exerts a force of equal magnitude and opposite direction on the former. (This is known as the weak law of action and reaction.)
Kepler's First Law: 1. The orbits of the planets are ellipses with the sun at one focus.
Kepler's Second Law: 2. A line from the planet to the sun sweeps over equal areas in equal intervals of time. This is equivalent to the statement of conservation of angular momentum.
Kepler's Third Law: 3. (T1/T2)²=(a1/a2)³, where T is the orbital period in years and a is the semimajor axis in AU. Also known as the harmonic law.
Conservation Law Angular Momentum: Angular momentum is conserved if the net external torque on the system is zero.
Conservation Law Linear Momentum: Linear momentum is conserved if the net external force acting upon a system is zero, and in inelastic collisions.
Conservation Law Energy (classical): Energy is conserved in elastic collisions.
Conservation Law Energy, Mass (quantum): Energy, mass is conserved except on short time scales for which they may violate in accordance with the energy-time uncertainty principle.
Conservation Law Electric charge: Electric charge is always conserved.
Conservation Law Baryon Number: Baryon number is always conserved.
Conservation Law Color: Color is always conserved.
Conservation Law Lepton Number: All lepton numbers are conserved.
Conserservation Law Strangeness: Strangeness is conserved in strong interactions, changes by one unit in weak interactions.
Conservation Law Isospin: Isospin is conserved in strong interactions.
Conservtion Law Isospin Z Component: Isospin Z component is conserved in strong interactions.
Zeroth Law of Thermodynamics: 0. If two systems are in thermal equilibrium with a third system, then they must be in thermal equilibrium with each other.
First Law of Thermodynamics: 1. dE=dQ-dW=Tds-PdV, where dE is the energy change, dQ is the change in heat, dW is the work done, T is the temperature, dS is the change in entropy, P is the pressure, and dV is the volume change. (dQ is an exact differential)
Second Law of Thermodynamics: 2. The second law of thermodynamics prohibits the construction of a perpetual motion machine of 'he second kind.' A consequence is the result that dQ=<TdS
Third Law of Thermodynamics: 3. As temperature goes to 0, the entropy S approaches a constant S0.
Combined Law of Thermodynamics: Combining the first and second laws gives the combined law of thermodynamics

dE-TdS+PdV =< 0

In terms of the Gibbs free energy,

dG =< 0
The Ideal Gas Law: PV = nRT

where n is the number of moles and R is the universal gas constant

PV = NkT

where N is the number of atoms and k is Boltzmann's constant
Boyle's Law: For a fixed amount of gaseous substance at constant temperature,

PV = constant
Charles' Law: For a fixed amount of gaseous substance at constant pressure,

V/T = constant
Avogadro's Hypothesis: At constant temperature and pressure

V/N = constant

where N is the number of atoms in the volume V.
The Strong Law of Action and Reaction: For every action force, there is a corresponding reaction force which is equal in magnitude and opposite in direction. Furthermore, the forces are central forces, i.e., they act along the line joining the particles.
Law of Reflection: The angle of incidence, measured relative to the normal, is equal to the angle of reflection, measured relative to the same normal.
Ohm's Law: V=IR

Where V is the voltage drop across the resistance R carrying the current I.
The Hubble Law: Hubble proposed in 1929 that almost all galaxies were moving away from the Milky Way. He postulated that recessional velocity v was directly proportional to distance r,

v=Hr

H is the Hubble constant.
Joule's Law: Joule's law gives the amount of heat Q liberated by current I flowing through a resistor with resistance R for a time t,

Q = Pt = I²Rt
Hooke's Law: For a spring below the elastic limit, the restoring force F exerted by the spring is given approximately by

F = -kx

where k is the stiffness constant of the spring and x is its displacement.
Lenz's Law: An induced current flows in a direction to create a magnetic field which will counteract the change in magnetic flux.
Mersenne's First Law: 1. When the tension on a string remains the same but the length L is varied, the period of the vibration is proportional to L. This is also known as Pythagoras's law.
Mersenne's Second Law: 2. When the length of a string is held constant but the tension T is varied, the frequency of oscillation is proportional to sqrt(T).
Mersenne's Third Law: 3. For different strings of the same length and tension, the period is proportional to sqrt(w), where w is the weight of the string.
Dalton's Law: Dalton's law states that the pressure of a gas mixture is equal to the sum of the partial pressures of the gases of which it is composed.
Steno Law: The angles between equivalent faces of crystals of the same substance, measured at the same temperature, are constant.

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