Nuclear Physics Review

A π⁰ meson is a particle with a mass of 2.4 x 10⁻²⁸ kg that can decay to produce photons. What is the order of magnitude of the energy contained in all the photons produced when a π⁰ meson completely decays?

• 10⁻³⁶ J

• 10⁻²⁷ J

• 10⁻²¹ J

• 10⁻¹⁹ J

• 10⁻¹¹ J

A negative beta particle and a gamma ray are emitted during the radioactive decay of a nucleus of 214/82 Pb. Which of the following is the resulting nucleus?

• 210/80 Hg

• 214/81 Tl

• 213/83 Bi

• 214/83 Bi

• 218/84 Po

A plutonium nucleus of mass M is at rest when it spontaneously emits a high-energy photon of frequency f. After the decay, the photon moves off in one direction and the nucleus recoils with speed v in the opposite direction. The nucleus' mass decreases by an amount Δm. Which of the following equations correctly represents the conservation of energy in the decay?

• (Δmc²) = ½(M-Δm)v² + hf

• (Δmc²) = ½(M-Δm)v² - hf

• Mc² = ½(M-Δm)v² + hf

• Mc² = ½(M-Δm)v² - hf

In a nuclear decay chain, a neptunium nucleus eventually becomes a thallium nucleus via a series of alpha and beta minus decays. The net reaction is shown. Which of the following is true of the number of alpha and beta particles produced?

• More alpha particles than beta particles are produced.

• More beta particles than alpha particles are produced.

• An equal number of alpha and beta particles are produced.

• There is no way to determine whether more alpha or beta particles are produced without knowing the individual steps in the process.

A proton is placed at rest in a uniform electric field. When the proton is released, it accelerates through a distance d, acquiring a speed v as a result. Next, an alpha particle is released from rest in the field and accelerates through the same distance. The speed acquired by the alpha particle is most nearly

• v/2

• v/√2

• √2v

• 2v

A molybdenum isotope (Z = 42) undergoes beta negative decay (β⁻). Based upon conservation of charge, what must be the atomic number (Z) of the product? Also, what particles decay and what particles are produced during β⁻ decay?

• A) Z = 41; in β⁻ decay, a neutron transforms into a proton, releasing an electron and a chargeless electron-antineutrino.

• B) Z = 41; in β⁻ decay, a proton transforms into a neutron, releasing an electron and a chargeless electron-antineutrino.

• C) Z = 43; in β⁻ decay, a neutron transforms into a proton, releasing an electron and a chargeless electron-antineutrino.

• D) Z = 43; in β⁻ decay, a proton transforms into a neutron, releasing an electron and a chargeless electron-antineutrino.

As shown in the diagram, nucleus X of mass mX collides with nucleus Y of mass mY that is momentarily at rest (mX + mY). Both nuclei then move off in the directions shown. It is unknown whether energy is lost during the interaction, but no other particles are produced. Which of the following claims is correct about which quantities must be the same before and after the collision?

• A) The total mass of the two nuclei

• B) The speed of nucleus X

• C) The total momentum of the two-nuclei system

• D) It cannot be determined without knowing if energy was lost during the collision

A scientist researching nuclear fusion is studying the reaction above in which two helium-3 nuclei react to form two hydrogen nuclei and a helium-4 nucleus. The scientist determines that the total mass of the two helium-3 nuclei is 1.00156 x 10^-26 kg and that the total mass of the two hydrogen nuclei and the helium-4 nucleus is 9.9596 x 10^-27 kg. How much energy is released in this reaction?

• 5.6*10^-29 J

• 5.04*10^-12 J

• 8.95*10^-10 J

• 9*10^-10 J

The scientist notes that this reaction involves a high-energy gamma ray photon. In what way is the photon associated with this reaction?

• An electron transitions to a higher allowed energy state and absorbs a photon of this energy difference.

• An electron transitions to a lower allowed energy state and emits a photon of this energy difference.

• A nucleus transitions to a higher energy state and absorbs a photon of this energy difference.

• A nucleus transitions to a lower energy state and emits a photon of this energy difference.

A stationary proton captures an electron of known speed, creating a hydrogen atom. No external forces act on the particles. Which of the following gives a correct method for determining the kinetic energy of the hydrogen atom and justifies the method?

• Calculate the kinetic energy of the electron, which equals the kinetic energy of the hydrogen atom because the collision is elastic.

• Reason that since the electron mass is much smaller than the proton mass, the motion of the electron will not affect the final motion of the hydrogen atom.

• Set the momentum of the electron equal to the momentum of the hydrogen atom and determine the speed of the hydrogen, because the collision is inelastic and only momentum is conserved. Use that speed to calculate the kinetic energy of the hydrogen atom.

• Measure the coulomb force that the proton exerts on the electron, and calculate the work done on the electron. This work equals the kinetic energy of the hydrogen atom