Question 1

If a K⁰ meson at rest decays in 0.9 × 10−¹⁰ s,how far will a K⁰ meson moving at 0.92 c travel through a bubble chamber? ( ) A) 6.3 cm B) 2.5 cm C) 0.97 cm D) 8.8 cm E) 0.70 cm

Accepted Answer

The answer of If a K⁰ meson at rest decays...

Question 2

The particle thought responsible for particle masses is: A) the graviton. B) the gluon. C) the Ω^- particle. D) the Higgs boson.

Accepted Answer

The Higgs boson is the particle thought to be responsible for particle masses. It was first theorized in the 1960s and was finally discovered in 2012 by the Large Hadron Collider. The Higgs boson is produced when two protons collide at very high speeds, and its discovery was a major breakthrough in particle physics.

Question 3

Which of the following is not conserved?
A) lepton number
B) baryon number
C) meson number
D) energy

Accepted Answer

Meson number is not conserved as mesons do not have a well-defined number and can be constantly created and destroyed. The other options (A, B, and D) are conserved quantities in various particle interactions.

Question 4

The cosmic background radiation appears compatible with a blackbody source at what temperature?
A) 0.000 3 K
B) 0.03 K
C) 3 K
D) 300 K

Accepted Answer

The cosmic background radiation appears to have a blackbody spectrum with a temperature of approximately 3 K, which is consistent with the idea that it is the remnant of the Big Bang. Choice A (0.0003 K) is too low and would correspond to a much colder radiation field, while choices B and D (0.03 K and 300 K) are much too high to match the observed spectrum.

Question 5

Which of the following particles is made of two or more smaller particles?
A) electron
B) photon
C) proton
D) None of the above.

Accepted Answer

The proton is made up of two up quarks and one down quark.

Question 6

According to the standard model,there are some cases in which a quark and its anti-quark have the same:
A) charge.
B) baryon number.
C) strangeness.
D) All of the above are always different.

Accepted Answer

The standard model predicts that quarks and anti-quarks have opposite electric charges and opposite baryon numbers. However, they can have the same strangeness. Strangeness is a quantum number that distinguishes particles containing strange quarks from those that do not. Anti-particles have the opposite strangeness value compared to their corresponding particles. Therefore, in some cases, a quark and its anti-quark can have the same strangeness but always have opposite charges and opposite baryon numbers.

Question 7

The Σ⁺,Σ⁰,and Σ^- all have strangeness of (-1).The collision of a proton and a neutron to produce a Σ⁰ and an anti-Σ^- cannot occur because it does not conserve: A) strangeness. B) charge. C) baryon number. D) All of the above.

Accepted Answer

The answer of The Σ⁺,Σ⁰,and Σ^- all have strangeness of...

Question 8

The charge of some quarks or anti-quarks is: A) 0. B) 1/2 (1.6 × 10−¹⁹)C. C) 1/3 (1.6 × 10−¹⁹)C. D) 1 (1.6 × 10−¹⁹)C.

Accepted Answer

Quarks have fractional electric charges, with a charge of +2/3 or -1/3 times the charge of an electron. Anti-quarks have the opposite charges to their corresponding quarks. Therefore, the correct option is C which states that the charge of some quarks or anti-quarks is 1/3 (1.6 × 10−19C).

Question 9

The Σ⁺,Σ⁰,and Σ^- all have strangeness of (-1).The collision of an anti-proton and a neutron may produce which of the following particles? A) Σ^- and Σ⁰ B) Σ⁺ and anti-Σ⁰ C) anti-Σ⁺ and Σ⁰ D) anti-Σ^- and Σ⁰

Accepted Answer

The answer of The Σ⁺,Σ⁰,and Σ^- all have strangeness of...

Question 10

Mesons are always composed of:
A) two quarks,one being classified as a quark and the other as an antiquark.
B) a quark of one color and an antiquark of the anticolor.
C) an up or down quark and a down or up antiquark.
D) Two of the above choices are correct.

Accepted Answer

Both choice A and C are correct. Mesons are always composed of a quark and an antiquark, and the combination can be either an up quark and a down antiquark, or a down quark and an up antiquark. Sometimes mesons are classified by their quark content, such as a pion being a combination of an up quark and a down antiquark. Alternatively, they can be classified by their charge, such as a neutral pion being composed of a combination of an up quark and a down antiquark or a down quark and an up antiquark. Therefore, choice A and C are both correct, making choice D the best answer.

Question 11

The strangeness of an anti-proton is:
A) +1.
B) 0.
C) -1.
D) -2.

Accepted Answer

The strangeness of an anti-proton is 0 because strangeness is a quantum number that describes the presence of strange quarks in a particle. An anti-proton, being the antiparticle of a proton, is composed of antiquarks, specifically two up antiquarks and one down antiquark, none of which are strange quarks. Therefore, its strangeness is 0.

Question 12

A proton and antiproton each with total energy 300 GeV collide head-on.What is the total energy (particles + energy)released?
A) 600 GeV
B) 300 GeV
C) zero
D) 450 GeV
E) ​150 GeV

Accepted Answer

When a proton and an antiproton collide, their mass energy (according to E=mc^2) plus their kinetic energy is converted into other forms of energy. Since each has a total energy of 300 GeV, the total energy released is 600 GeV.

Question 13

The spin of all quarks is:
A) 0.
B) 1/2.
C) 1.
D) 1/3 or 2/3.

Accepted Answer

The spin of all quarks is 1/2, which is the same as the spin of electrons and other fermions. The other options are not correct: (A) is not true because quarks are spin-1/2 particles; (C) is not true because quarks have a spin of 1/2, not 1; and (D) is not true because quarks have a spin of exactly 1/2, not 1/3 or 2/3.

Question 14

According to the standard model,a quark and its antiquark may have the same:
A) spin.
B) baryon number.
C) charge.
D) All of the above may be the same.

Accepted Answer

Quarks and their corresponding antiquarks have the same spin, as spin is a quantum property that does not change when particle-antiparticle pairs are created or annihilated. However, they have opposite baryon numbers and charges.

Question 15

Mesons are composed of ________ quarks,and baryons are composed of ________ quarks.
A) two,two
B) two,three
C) three,two
D) three,three

Accepted Answer

Mesons are composed of one quark and one anti-quark, thus two quarks in total. Baryons are composed of three quarks. Therefore, option B is the correct choice, as it states that mesons are composed of two quarks (one quark and one anti-quark) and baryons are composed of three quarks.

Question 16

If two quarks in an anti-proton have the color anti-red and anti-blue,the third quark must have the color:
A) red.
B) blue.
C) anti-purple.
D) anti-green.

Accepted Answer

The third quark in the anti-proton must have the color anti-green in order to combine with the anti-red and anti-blue colors of the other two quarks to form a colorless state, as required by the strong force.

Question 17

The microwave background radiation:
A) represents the leftover glow from the Big Bang.
B) was discovered by Penzias and Wilson.
C) had its slight non-uniformity measured by COBE.
D) All of the above.

Accepted Answer

The microwave background radiation represents the leftover glow from the Big Bang and was discovered by Penzias and Wilson. Its slight non-uniformity was measured by COBE.

Question 18

Experimentally,strange particles can be produced in abundance,but they decay relatively slowly.This occurs because strangeness:
A) is conserved in both their production and decay.
B) is conserved in their production but not in their decay.
C) is conserved in their decay but not in their production.
D) is not conserved in either their production or their decay.

Accepted Answer

Strange particles are produced through strong and weak interactions, which conserve strangeness. However, they can undergo weak decays that violate the conservation of strangeness. This causes them to decay relatively slowly compared to other particles. Therefore, option B is correct as strangeness is conserved in their production but not in their decay.

Question 19

The Big Bang occurred:
A) about 15 to 20 billion years ago.
B) about 5 to 7 thousand years ago.
C) about 4 to 6 billion years ago.
D) infinitely far in the past.

Accepted Answer

The most widely accepted scientific theory is that the Big Bang occurred about 13.8 billion years ago, with a margin of error of approximately 100 million years. Option B is incorrect as the Earth is believed to be around 4.54 billion years old, and option C is incorrect as this refers to the age of the Earth as well as the estimated age of our solar system. Option D is incorrect as the Big Bang is not considered an infinitely recurring event.

Question 20

The weak force is mediated by: A) the W⁺ boson. B) the W^- boson. C) the Z⁰ boson. D) All of the above.

Accepted Answer

The weak force is mediated by the W and Z bosons, which include the variants listed in all the options, indicating that all of the above are correct representations of the particles involved in mediating the weak force.

Quiz 30: Nuclear Energy and Elementary Particles

If a K⁰ meson at rest decays in 0.9 × 10−¹⁰ s,how far will a K⁰ meson moving at 0.92 c travel through a bubble chamber? ( )

The particle thought responsible for particle masses is:

Which of the following is not conserved?

The cosmic background radiation appears compatible with a blackbody source at what temperature?

Which of the following particles is made of two or more smaller particles?

According to the standard model,there are some cases in which a quark and its anti-quark have the same:

The Σ⁺,Σ⁰,and Σ^- all have strangeness of (-1) .The collision of a proton and a neutron to produce a Σ⁰ and an anti-Σ^- cannot occur because it does not conserve:

The charge of some quarks or anti-quarks is:

The Σ⁺,Σ⁰,and Σ^- all have strangeness of (-1) .The collision of an anti-proton and a neutron may produce which of the following particles?

Mesons are always composed of:

The strangeness of an anti-proton is:

A proton and antiproton each with total energy 300 GeV collide head-on.What is the total energy (particles + energy) released?

The spin of all quarks is:

According to the standard model,a quark and its antiquark may have the same:

Mesons are composed of quarks,and baryons are composed of quarks.

If two quarks in an anti-proton have the color anti-red and anti-blue,the third quark must have the color:

The microwave background radiation:

Experimentally,strange particles can be produced in abundance,but they decay relatively slowly.This occurs because strangeness:

The Big Bang occurred:

The weak force is mediated by: