# Worksheet: Subatomic Particles

In this worksheet, we will practice applying quantum number conservation laws to interactions between subatomic particles.

Q1:

Identify the missing particle in the reaction.

• A
• B
• C
• D
• E

Q2:

Identify the missing particle in the reaction .

• A
• B
• C
• D
• E

Q3:

Identify the missing particle in the reaction shown.

• A
• B
• C
• D
• E

Q4:

Identify the missing particle in the reaction .

• A
• B
• C
• D
• E

Q5:

Identify the missing particle in the reaction shown.

• A
• B
• C
• D
• E

Q6:

Consider the following decays of unstable subatomic particles. Which of these decays cannot occur because the law of conservation of lepton number would be violated?

• A
• B
• C
• D
• E

Q7:

The decays of unstable subatomic particles can be described using equations: Which of the decays shown cannot occur because the law of conservation of lepton number would be violated?

• A
• B
• C
• D
• E

Q8:

Consider the following decays of unstable subatomic particles: Which of these decays cannot occur because the law of conservation of lepton number would be violated?

• A
• B
• C
• D
• E

Q9:

An electron has a rest mass of 0.511 MeV. How much energy is released when an electron and a positron at rest annihilate each other?

Q10:

A neutral pion has a rest mass of 135.0 MeV. Assuming conservation of momentum, what is the energy of each ray produced in the decay of a neutral pion at rest. The reaction produces two equal energy photons.

Q11:

An electron has a rest mass of 0.511 MeV. When both an electron and a positron are at rest, they can annihilate each other according to the reaction shown. The energies of the photons produced in the reaction are equal to each other, as are the photon’s momenta and their frequencies.

What is the energy of one of the photons?

• A
• B
• C
• D
• E

What is the momentum of one of the photons?

• A kg⋅m/s
• B kg⋅m/s
• C kg⋅m/s
• D kg⋅m/s
• E kg⋅m/s

What is the frequency of one of the photons?

• A Hz
• B Hz
• C Hz
• D Hz
• E Hz

Q12:

A negative pion has a rest mass of . The primary decay mode for negative pions is . A muon has a rest mass of , while a neutrino has negligible rest mass and a momentum . A pion that is at rest undergoes a primary mode decay.

How much energy is released in this decay?

How much energy does the muon take from the reaction?

How much energy does the neutrino take from the reaction?

Q13:

A charmed sigma particle is composed of an up quark, a down quark, and a charm quark. What is the charmed sigma particle’s net charge due to the charge of its constituent quarks?

• A
• B
• C
• D
• E

Q14:

An omega particle is composed of three strange quarks. What is the omega particle’s net charge due to the charge of its constituent quarks?

• A
• B
• C
• D
• E

Q15:

A particle is composed of an up quark, a down quark, and a bottom quark. What is the particle’s net charge due to the charge of its constituent quarks?

Q16:

The hypothetical strong nuclear reaction violates at least one of the conservation laws relating to the properties of fundamental particles.

What is the net strangeness before the reaction?

What is the net strangeness after the reaction?

What is the baryon number before the reaction?

What is the baryon number after the reaction?

Q17:

The hypothetical strong nuclear reaction violates at least one of the conservation laws relating to the properties of fundamental particles.

What is the net strangeness before the reaction?

What is the net strangeness after the reaction?

Q18:

A neutron is composed of one up quark and two down quarks. What is the neutron’s net charge due to the charge of its constituent quarks?

Q19:

A hypothetical meson is formed from a green strange quark and an anti-green up quark.

Determine the charge of the meson.

• A
• B
• C
• D0
• E

Determine the strangeness of the meson.

• A0
• B
• C1
• D-1
• E2

Q20:

A hypothetical meson is formed from a red strange quark and an anti-red strange quark.

Determine the charge of the meson.

• A
• B
• C0
• D
• E

Determine the strangeness of the meson.

Q21:

Hypothetical experimental results indicate a free particle with charge . Assuming that this particle is actually a free quark, which of the following quarks could it be?

• ATop quark
• BUp quark
• CStrange quark
• DCharm quark

Q22:

Which of the following reactions cannot happen because it would violate the law of conservation of baryon number?

• A
• B
• C
• D
• E

Q23:

The hypothetical strong nuclear reaction violates at least one of the conservation laws relating to the properties of fundamental particles.

What is the baryon number before the reaction?

What is the baryon number after the reaction?

Q24:

A hypothetical meson is formed from a blue down quark and an anti-blue down quark.

Determine the charge of the meson.

• A0
• B
• C
• D
• E

Determine the strangeness of the meson.

Q25:

The hypothetical strong nuclear reaction violates at least one of the conservation laws relating to the properties of fundamental particles.

What is the net strangeness before the reaction?

What is the net strangeness after the reaction?

What is the lepton number before the reaction?

What is the lepton number after the reaction?