relativity

A particle called neutral pi meson (or pion) decays into two photons (and nothing else).If the pion (whose rest mass is 135Mev) is initially at rest,

What are the energies of the photons?

How are they moving with respect to each other ?

  1. 👍 0
  2. 👎 0
  3. 👁 188
  1. It's easier to start with the second part of the question. The momentum of the poin is zero, so the sum of the momenta of the two photons (p1 and p2) is zero:

    p1 + p2 = 0 ------->

    p1 = - p2

    Then because the energy of a photon with momentum p = |p| c, you see that the energies of the two photons are equal. The sum of the energies of the two photons has to be 135 MeV, because of energy conservation, so each photon has half this energy.

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second?

    asked by anon yo on October 6, 2016
  2. Nuclear Chemistry

    The half- life of a positron is very short. it reacts with an electron, and the masses of both are converted to two gamma-ray photons: (0e+1)+ (0e-1)---> 2γ (the 0 in front of e is the mass # and behind it is the atomic #) (γ

    asked by Anonymous on June 13, 2012
  3. Chemistry- Dr. Bob

    Question 1 Calculate the wavelength (in nm) of the red light emitted by a neon sign with a frequency of 4.74 x 1014 Hz. A) 704 nm B) 158 nm C) 466 nm D) 633 nm E) 142 nm My answer: D.633 nm Question 2 How many photons are

    asked by Anonymous on November 7, 2015
  4. physics

    Two forces, 1 = (3.85 − 2.85) N and 2 = (2.95 − 3.65) N, act on a particle of mass 2.10 kg that is initially at rest at coordinates (−2.30 m, −3.60 m). (a) What are the components of the particle's velocity at t = 11.8 s?

    asked by Anonymous on March 7, 2014
  1. science

    the velocity of a particle is given by v=[16t^2i+4t^3j +(5t+2)k]m/s, where t is in seconds. If the particle is at the origin when t=0, determine the magnitude of the particle's acceleration when t=2s. What is the x,y,z coordinate

    asked by sarah on November 3, 2008
  2. physics

    An atom is normally electrically neutral .Why then should an alpha particle be deflected by the atom under any circumstances?

    asked by aman on June 18, 2008
  3. Physics

    An atomic nucleus at rest decays radioactively into an alpha particle and a nucleus smaller than the original. What will be the speed of this recoiling nucleus if the speed of the alpha particle is 2.20E+05 m/s? Assume the

    asked by Victoria on April 10, 2015
  4. Chemistry!

    1. Write balanced equations for each of the following processes. a. Chromium- 51, which targets the spleen and is used as a tracer in studies of red blood cells, decays by electron capture. b. Iodine-131, used to treat hyperactive

    asked by Sharon on January 27, 2011
  1. CHEM

    the nuclide 232 Th 90 is radioactive. when one of the atoms decays, a series of alpha and beta particle emission occurs, taking the atom through many transformations to end up as an atom of 208 Pb 82. How many alpha particles are

    asked by Gabe on March 4, 2008
  2. Chemistry

    1. Write balanced equations for each of the following processes. a. Chromium- 51, which targets the spleen and is used as a tracer in studies of red blood cells, decays by electron capture. b. Iodine-131, used to treat hyperactive

    asked by Sharon on January 26, 2011
  3. Biology

    Gabriela is sick with a bad cold. Her immune system is defending her body against the invading virus. The first line of defense is cells called macrophages, which attack viral particles. The cells eliminate viral particles in a

    asked by go commit not ok on November 14, 2018
  4. physics

    An atomic nucleus at rest decays radioactively into an alpha particle and a different nucleus.

    asked by Anonymous on March 2, 2015

You can view more similar questions or ask a new question.