# Questions tagged [conservation-laws]

The statement that a property of a system does not change if the system is isolated.

2,670 questions
Filter by
Sorted by
Tagged with
33 views

### Photon absorbed, identical Photon re-emitted [closed]

I believe I frequently see it stated that a photon is absorbed and an identical photon is emitted. How can the energy in equal the energy out, with no loss?
41 views

### What is the mathematical derivation for no diffusion term in the mass continuity equation of the Navier-Stokes/Euler equations?

In this post the fact that the mass continuity equation in a mixture of gases has no diffusion term, i.e., $$\frac{\partial\rho}{\partial t}+\nabla\cdot(\rho\vec{v})=0$$ has been discussed. ...
53 views

### What are the symmetries of standard model and its conservation laws? [closed]

Is there like a list of symmetries in the standard model with associated conservation laws?
50 views

### Physics of tennis hit

If one takes notice the tennis players hit the ball on the right corner that way: Their last step before the hit is on the right foot, then they hit and then their left foot goes up in the air about ...
20 views

### Cosmic strings and conservation of momentum

I've been told that cosmic strings useful don't give of gravity. I've been told that if an objects passive and active gravitational masses differ then this will result in a violation of conservation ...
53 views

### Continuity and Bernoulli's Equation in a vertical pipe with different cross sections [closed]

Consider the following situation where the amount of water that goes through a cross section $A_1$ per second is the same as it goes through $A_0$ (just continuity) and is always constant: I setup ...
225 views

### Null conserved angular momentum

If the angular momentum of a particle is conserved and it is also 0, then is it true that the particle moves along a line? If so, how can we derive the equation for the trajectory from both the above ...
18 views

83 views

### Is gauge symmetry necessary for charge conservation?

The common view is that gauge symmetry is necessary for conservation of charge(s) in Yang-Mills theory. But one thing I have never been able to get out of my head is, if there isn't any other possible ...
91 views

### When we move do we "borrow" momentum from the earth?

In 2001 Arthur C Clarke wrote: Like a ball on a cosmic pool table, Discovery had bounced off the moving gravitational field of Jupiter, and had gained momentum from the impact... Yet there was no ...
5k views

### Is angular momentum just a convenience?

I'm wondering whether angular momentum is just a convenience that I could hypothetically solve any mechanics problems without ever using the concept of angular momentum. I came up with this question ...
1 vote