How is momentum conserved in relativity?
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How is momentum conserved in relativity?
Momentum is conserved whenever the net external force on a system is zero. Relativistic momentum is defined in such a way that conservation of momentum holds in all inertial frames. Whenever the net external force on a system is zero, relativistic momentum is conserved, just as is the case for classical momentum.
Why is 4-momentum conserved?
With this approach it is less clear that the energy and momentum are parts of a four-vector. The energy and the three-momentum are separately conserved quantities for isolated systems in the Lagrangian framework. Hence four-momentum is conserved as well.
Is 4-momentum always conserved?
Just as momentum is conserved in any ordinary collision, elastic or inelastic, so 4-momentum is conserved in any relativistic collision, elastic or inelastic.
Is 4-momentum an invariant?
In the literature of relativity, space-time coordinates and the energy/momentum of a particle are often expressed in four-vector form. The invariance of the energy-momentum four-vector is associated with the fact that the rest mass of a particle is invariant under coordinate transformations. …
How is relativistic momentum different from the classical concept of momentum?
At low velocities, relativistic momentum is equivalent to classical momentum. Relativistic momentum approaches infinity as u approaches c. This implies that an object with mass cannot reach the speed of light. Relativistic momentum is conserved, just as classical momentum is conserved.
What is the four momentum of a photon?
The 4-momentum is defined as p=mU where m is the rest mass of the particle and U is the 4-velocity. Now I am confused as to how this applies to a photon for which one can’t define U since there can be no rest frame for a photon.
Why is momentum not always conserved?
Momentum is not conserved if there is friction, gravity, or net force (net force just means the total amount of force). What it means is that if you act on an object, its momentum will change. This should be obvious, since you are adding to or taking away from the object’s velocity and therefore changing its momentum.
How do you prove something is a 4-vector?
If you have a valid tensorial expresson (i.e. one that obeys the rules of tensor analysis) in which everything else except your 4-component object is a tensor of some rank or other, and you know the expression holds in all coordinate systems, then your object is a 4-vector.