What is the energy loss of a solid sphere hitting a wall obliquely?

In summary, the conversation is about understanding a formula for the energy of a gamma photon after it undergoes compton scattering with a stationary electron. The formula is derived using conservation of energy and momentum, and includes the electron's kinetic energy. The conversation then shifts to a separate problem involving calculating the energy lost by a solid sphere hitting a solid wall obliquely, for which the poster is seeking help and resources.
  • #1
physmurf
27
0
So, I am reading about a compton scattering problem, and I don't understand part of the derivation of a formula. I will explain my confusion.

If a gamma photon with energy [tex]E_{\gamma}[/tex], undergoes compton scattering with an electron which is at rest, how does one arrive at the following expression?

[tex]E^{'}_{\gamma}=\frac{E_{\gamma}}{1+(2E_{\gamma}/m_{o}c^{2})}[/tex]

So far it says we start with the conservation of energy and momentum:
[tex]E_{\gamma}=E^{'}_{\gamma}+E_{e} \ \ (eqn 1)[/tex]
[tex]\frac{E_{\gamma}}c=P_{e}-\frac{E^{'}_{\gamma}}{c}\ \ (eqn 2)[/tex]

From eqn 2 we get:
[tex]E_{\gamma}+E^{'}_{\gamma}=p_{e}c=\sqrt{(E_{e}+m_{o}c^{2})^{2}-(m_{o}c^{2})^{2}}[/tex]

This is where I am confused. I don't understand where the term inside of the radical comes from. Any ideas?
 
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  • #2
physmurf said:
[tex]E_{\gamma}+E^{'}_{\gamma}=p_{e}c=\sqrt{(E_{e}+m_{o}c^{2})^{2}-(m_{o}c^{2})^{2}}[/tex]

The [itex]E_e[/itex] in the square root on the right is the electron's kinetic energy, which most books call [itex]K_e[/itex]. [itex]E_e[/itex] usually means the total energy:

[tex]E_e = K_e + m_0 c^2[/tex]

Using this notation, the relationship between energy, momentum and mass is

[tex]E^2 = (pc)^2 + (m_0 c^2)^2[/tex]

so

[tex]p_e c = \sqrt {E_e^2 - (m_0 c^2)^2} = \sqrt {(K_e + m_0 c^2)^2 - (m_0 c^2)^2}[/tex]
 
Last edited:
  • #3
hi all,

a similar post for me. pls help me.
i need to calculate the energy lost by a solid sphere (~ 0.5 mm dia) on hitting the solid wall obliquely.
i know the tangetial and normal velocities and the restitution coefficients. what other parameters do i need to know ??

help with the expression or a reference to articles in the web would be of great help.

thanks you.
 

What is momentum?

Momentum is a physics concept that describes the quantity of motion an object has. It is calculated by multiplying an object's mass by its velocity.

What is the relationship between momentum and energy?

Momentum and energy are both related to an object's motion. However, momentum is a measure of an object's quantity of motion, while energy is a measure of an object's ability to do work. In some cases, an object's momentum can be converted into energy, such as in a collision.

How is momentum conserved?

Momentum is conserved in a closed system, meaning that it remains constant as long as there are no external forces acting on the system. This is known as the law of conservation of momentum.

What are the units of momentum?

The units of momentum are kg*m/s, which can also be written as N*s (newton-seconds). This unit combines the units of mass (kg) and velocity (m/s).

Can momentum be negative?

Yes, momentum can be negative. This occurs when an object is moving in the opposite direction of a chosen positive direction. It is important to keep track of the direction of an object's momentum in order to accurately describe its motion.

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