All Questions
Tagged with conservation-laws homework-and-exercises
396
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Proving conservation of supercurrent
I am trying to prove that the supercurrent $J^\mu = \gamma^{\nu \rho} F^A_{\nu \rho} \gamma^\mu \lambda^A $ is conserved in ${\cal N}=1$ SUSY Yang-Mills theory ( basically trying to reproduce equation ...
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Finding the Noether current
I'm currently reading "QFT for the gifted Amateur by Lancaster and Blundell, and in a lot of the problems I'm a bit unsure of how to do them, an example asked
"Consider a system ...
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Confusion in conservation of momentum [closed]
Two masses $m_1$ and $m_2$ are attached to the two ends of a rope that is sent through a pulley. Then a mass $M$ is dropped onto the mass $m_1$ from a $h$ height. So when the law of conservation of ...
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Im confused on how conservation of momentum works mathematically for a problem involving a skater throwing two weights from rest [closed]
Here's the question.
A 40-kg skateboarder on a 3-kg board is training with two 5-kg weights. Beginning from rest, she throws the weights horizontally, one at a time from her board. The speed of each ...
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Do we know that energy of a system is conserved if no external forces do work on it?
This question is from K&K's intro book on mechanics. The larger block with the quarter circle missing has mass $M$ and the smaller block has mass $m$. The goal is to find the speed $v$ of the ...
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Deriving conserved currents from variation of action
I am reading An Modern Introduction to Quantum Field Theory by Maggiore. I have difficulty following the calculation of $\delta ( d^4 x)$ and $\delta (\partial_\mu \phi_i)$. Also, wonder whether the ...
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Deriving continuity equation from 4-current of a charged particle
how can i check that following 4-current for a single charged particle
$$j^{\mu}(x)=qc\int d\tau u^{\mu}(\tau)\delta^{4}(x-r(\tau))$$
satisfies continuity equation $$\partial_\mu j^\mu = 0.$$
user391340
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Two bodies that collided inelastically and rebounded [closed]
I can't find the solution to this problem.
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Ball collisions
When two balls collide directly, the impulse of the collision acts along the line of centers, so the momentum along this direction is not conserved. Therefore, I can only use the conservation of ...
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Q1.1(a) Sakurai Advanced Quantum Mechanics For energy-momentum tensor [closed]
I need to prove that the energy-momentum tensor density is defined as:
\begin{equation}
\mathcal{T}_{\mu\nu}=-\frac{\partial \phi}{\partial x_\nu}\frac{\partial\mathcal{L}}{\partial(\frac{\partial \...
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Linear Momentum conservation
Take a 1kg point mass at the end of a 1 meter massless rod, free to rotate about a pivot at the other end of the rod. If I apply 1 unit of force to the point mass at a right angle to the rod, the ...
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Three masses connected by a string (momentum conservation) [closed]
Three identical balls each of mass m = 0.5 kg are connected with each other as shown in figure and rest over a smooth horizontal table. At moment t=0, ball B is imparted a horizontal velocity v=9m/s. ...
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On the continuity condition of the Klein-Gordon equation
I have to show that $\partial_\mu j^\mu = 0$ for the four-current $j^\mu = \frac{i}{2m}\left(\phi^*\partial^\mu\phi - \phi\:\partial^\mu\phi^*\right)$.
Using the Leibniz rule, one gets to
$$\partial_\...
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Using Galilean transformation to solve a question with a block-spring-block system [closed]
I am currently practicing for my PHYS 101 major test and encountered this question:
In Figure 11, block 1 (mass 2.50 kg) is moving rightward at 10.0 m/s
and block 2 (mass
6.20 kg) is moving rightward ...
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Conservation of energy/momentum doubt in bullet embedding into block
A bullet of mass 10$\,$g travels horizontally with speed of 100$\,$m/s and is absorbed by a wooden block of mass 990$\,$g suspended by a string. Find the vertical height through which the block rises, ...
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