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Conservation Laws

A conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. The physical result concerning conservation laws is Noether’s theorem. This theorem states that there is a one-to-one correspondence between conservation laws and differentiable symmetries of physical systems.

Exact laws are conservation laws that are said to be more precise and never been shown to be violated. A list of exact laws is as followed
- Conservation of mass-energy
- Conservation of linear momentum
- Conservation of angular momentum
- Conservation of electric charge
- Conservation of color charge
- Conservation of weak isospin
- Conservation of probability
- CPT symmetry
- Lorentz symmetry

Approximate conservation laws are approximately true in particular situations. These situations can be low speeds or short time scales.
- Conservation of mass
- Conservation of baryon number
- Conservation of lepton number
- Conservation of flavor
- Conservation of parity
- Invariance under time reversal
- CP symmetry

Categories within Conservation Laws

Conservation of Energy

Postings: 179

The total amount of energy in an isolated system remains constant over time.

Angular Momentum

Postings: 164

When no external torques act on an object or a closed system, no changes to the angular momentum can occur.

Calculation of number of Uranium-235 nuclei

In a problem, I'm supposed to calculate the number of Uranium-235 nuclei in 10^4 Kg of Uranium. The answer book gives Number of U-235 nuclei = (10^4)*(1000/238)(6*10^23)(0.02) = 5*10^26 I don't know where the factor 6*10^23 and (1000/238) come from. The 0.02 come from the fact that 2% of Uranium is U-235 and the rest is U

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Motion in Straight-Line

Freeway Traffic. According to a Scientific American article (May, 1990), current freeways can sustain about N vehicles per lane per hour in smooth traffic flow at speed . Above that figure the traffic flow becomes "turbulent" (stop-and-go). 1) If a vehicle is of length L on the average, what is the average spacing between ve

Conservation Laws- Inelastic collison

In an inelastic collision, is the final total momentum more than the initial momentum, less than the initial momentum or is it the same as the initial momentum?

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"A person who is properly constrained by an over-the-shoulder seat belt has a good chance of surviving a car collision if the decceleration does not exceed 26.0 G's (1.00 G = 9.8 m/s^2). Assuming uniform decceleration of this value, calculate the distance over which the front end of the car must be designed to collapse if a cras