Question 1

Consider the possibility that a neutron could decay into a proton and a pion.What,if any,of the following conservation laws would this process violate?

Accepted Answer

A)  conservation of energy 
B)  conservation of lepton number 
C)  conservation of charge 
D)  conservation of baryon number 
E)  None of the above laws would be violated.

Question 2

If the density of the universe is less than the critical density,then the total energy of the universe is

Accepted Answer

A)  positive. 
B)  negative. 
C)  zero.

Question 3

Suppose that the Hubble constant had the value 35.0 km/s per million light-years. (1y=3.156 x 10⁷s ,m_h ≈ m_proton = 1.67 × 10^-27 kg,c = 3.00 × 10⁸ m/s, 1 light-year =9.461 x 10¹⁵ m,G = 6.67 × 10^-11 N ∙ m²/kg²) (a)What would be the maximum density the universe could have that would still allow it to expand forever? (b)Under the conditions of part (a),how many hydrogen atoms would we expect to find,on the average,in a volume of space measuring 3.00 m by 8.00 m by 8.00 m?

Accepted Answer

The answer of Suppose that the Hubble constant had the...

Question 4

Luminous (normal)matter makes up approximately what percentage of the known matter in the universe?

Accepted Answer

A)  5% 
B)  15% 
C)  60% 
D)  95%

Question 5

A giant star in another galaxy exploded 67 million years ago,forming a supernova.The event is observed by an astronomer on Earth.Estimate the speed at which the supernova (and its galaxy)recedes from Earth if the Hubble constant is 22 km/s per million light-years.  ,1 ly = 9.461 × 1015 m,1 y = 3.156 × 107 s)

Accepted Answer

A)  1200 km/s 
B)  670 km/s 
C)  1500 km/s 
D)  2700 km/s 
E)  4700 km/s

Question 6

The decay n → p+ + e- + γ does NOT occur because it would violate conservation of

Accepted Answer

A)  baryon number. 
B)  lepton number. 
C)  charge. 
D)  energy.

Question 7

Given that the reaction n + π+ → p can occur and that the quark composition of the neutron is udd and that of the proton is uud,what must be the quark composition of the π+ meson?

Accepted Answer

A)  u  
B)   d 
C)  d  
D)  u  
E)   d

Question 8

Which of the following particles is NOT made up of quarks? (There may be more than one correct choice.)

Accepted Answer

A)  proton 
B)  neutron 
C)  electron 
D)  π-meson 
E)  neutrino

Question 9

The reaction p +  → e+ + γ is NOT possible because

Accepted Answer

A)  baryon number is not conserved. 
B)  lepton number is not conserved. 
C)  charge is not conserved. 
D)  energy is not conserved. 
E)  This reaction IS possible.

Question 10

If a galaxy is receding from us at 0.10c.Use Hubble's law to estimate the distance to this galaxy if the Hubble constant is 22 km/s per million light-years.(c = 3.00 × 108 m/s,  ,1 y = 3.156 × 107 s)

Accepted Answer

A)  1.4 × 109 ly 
B)  6.6 × 105 ly 
C)  6.6 × 105 Mly 
D)  2.2 Mly 
E)  1.4 × 107 Mly

Question 11

Suppose you were to try to create a proton-antiproton pair by annihilation of two very high-energy gamma rays of the same wavelength heading toward each other.The proton and the anti-proton have the same masses,but opposite charges.What would be the minimum energy needed for each photon? (e = 1.60 × 10-19 C,mproton = 1.67 × 10-27 kg,

Accepted Answer

A)  1.022 MeV 
B)  12.2 MeV 
C)  1880 MeV 
D)  939 MeV 
E)  223 MeV

Question 12

Which of the following particles are made up of quarks? (There may be more than one correct choice.)

Accepted Answer

A)  nucleons 
B)  hadrons 
C)  neutrinos 
D)  muons 
E)  mesons

Question 13

The voltage across the dees of a cyclotron is 30,000 V.How many revolutions do the protons go through in reaching a kinetic energy of 21 MeV? (1 eV = 1.60 × 10-19 J,  ,mproton = 1.67 × 10-27 kg)

Accepted Answer

A)  2.0 million 
B)  1400 
C)  700 
D)  350 
E)  35

Question 14

Consider the negative pion,π^-. (a)What combination of up and down quarks makes up this particle? (b)Is the π^-a baryon or a meson? (c)Is the π^- a lepton or a hadron?

Accepted Answer

The answer of Consider the negative pion,π^-. (a)What combination of up...

Question 15

Consider the decay πo → μ- + e+.This decay is

Accepted Answer

A)  allowed. 
B)  forbidden because conservation of energy is violated. 
C)  forbidden because conservation of baryon number is violated. 
D)  forbidden because conservation of mass is violated. 
E)  forbidden because conservation of lepton numbers is violated.

Question 16

How many different kinds of leptons are known to exist,including antiparticles as different kinds?

Accepted Answer

A)  4 
B)  6 
C)  8 
D)  2 
E)  12

Question 17

A neutral η0 (having mass 0.642 u)that is at rest decays into two gamma ray photons.What is the energy in MeV of each photon? (1 u = 931.5 MeV/c2)

Accepted Answer

A)  299 MeV 
B)  597 MeV 
C)  1190 MeV 
D)  199 MeV 
E)  149 MeV

Question 18

A galaxy is observed receding from Earth with a speed of 9800 km/s.A redshifted spectral line originating in the galaxy is compared to the same spectral line originating in the laboratory.If Hubble's law is valid for this galaxy,what is the ratio of the wavelength of the redshifted line to that of the unshifted line if the Hubble constant is 22 km/s per million light-years? (c = 3.00 × 108 m/s,1 ly = 9.461 × 1015 m,1 y = 3.156 × 107 s)

Accepted Answer

A)  1.033 
B)  1.052 
C)  1.072 
D)  1.091 
E)  1.130

Question 19

The Large Hadron Collider (LHC)near Geneva,Switzerland is an example of a

Accepted Answer

A)  linear accelerator. 
B)  cyclotron. 
C)  synchrotron. 
D)  None of the above

Question 20

Particles that do not interact via the strong force but do interact via the weak nuclear force (and presumably by the much weaker gravitation force)are called

Accepted Answer

A)  baryons. 
B)  mesons. 
C)  hadrons. 
D)  leptons. 
E)  nucleons.

Exam 44: Particle Physics and Cosmology

Consider the possibility that a neutron could decay into a proton and a pion.What,if any,of the following conservation laws would this process violate?

If the density of the universe is less than the critical density,then the total energy of the universe is

Luminous (normal) matter makes up approximately what percentage of the known matter in the universe?

The decay n → p⁺ + e^- + γ does NOT occur because it would violate conservation of

Given that the reaction n + π⁺ → p can occur and that the quark composition of the neutron is udd and that of the proton is uud,what must be the quark composition of the π⁺ meson?

Which of the following particles is NOT made up of quarks? (There may be more than one correct choice.)

The reaction p + → e⁺ + γ is NOT possible because

If a galaxy is receding from us at 0.10c.Use Hubble's law to estimate the distance to this galaxy if the Hubble constant is 22 km/s per million light-years.(c = 3.00 × 10⁸ m/s, ,1 y = 3.156 × 10⁷ s)

Which of the following particles are made up of quarks? (There may be more than one correct choice.)

The voltage across the dees of a cyclotron is 30,000 V.How many revolutions do the protons go through in reaching a kinetic energy of 21 MeV? (1 eV = 1.60 × 10^-19 J, ,m_proton = 1.67 × 10^-27 kg)

Consider the negative pion,π^-. (a)What combination of up and down quarks makes up this particle? (b)Is the π^-a baryon or a meson? (c)Is the π^- a lepton or a hadron?

Consider the decay π^o → μ^- + e⁺.This decay is

How many different kinds of leptons are known to exist,including antiparticles as different kinds?

A neutral η⁰ (having mass 0.642 u) that is at rest decays into two gamma ray photons.What is the energy in MeV of each photon? (1 u = 931.5 MeV/c²)

The Large Hadron Collider (LHC) near Geneva,Switzerland is an example of a

Particles that do not interact via the strong force but do interact via the weak nuclear force (and presumably by the much weaker gravitation force) are called

Exam 44: Particle Physics and Cosmology

Consider the possibility that a neutron could decay into a proton and a pion.What,if any,of the following conservation laws would this process violate?

If the density of the universe is less than the critical density,then the total energy of the universe is

Luminous (normal) matter makes up approximately what percentage of the known matter in the universe?

The decay n → p+ + e- + γ does NOT occur because it would violate conservation of

Given that the reaction n + π+ → p can occur and that the quark composition of the neutron is udd and that of the proton is uud,what must be the quark composition of the π+ meson?

Which of the following particles is NOT made up of quarks? (There may be more than one correct choice.)

The reaction p + → e+ + γ is NOT possible because

If a galaxy is receding from us at 0.10c.Use Hubble's law to estimate the distance to this galaxy if the Hubble constant is 22 km/s per million light-years.(c = 3.00 × 108 m/s, ,1 y = 3.156 × 107 s)

Which of the following particles are made up of quarks? (There may be more than one correct choice.)

The voltage across the dees of a cyclotron is 30,000 V.How many revolutions do the protons go through in reaching a kinetic energy of 21 MeV? (1 eV = 1.60 × 10-19 J, ,mproton = 1.67 × 10-27 kg)

Consider the negative pion,π-. (a)What combination of up and down quarks makes up this particle? (b)Is the π- a baryon or a meson? (c)Is the π- a lepton or a hadron?

Consider the decay πo → μ- + e+.This decay is

How many different kinds of leptons are known to exist,including antiparticles as different kinds?

A neutral η0 (having mass 0.642 u) that is at rest decays into two gamma ray photons.What is the energy in MeV of each photon? (1 u = 931.5 MeV/c2)

The Large Hadron Collider (LHC) near Geneva,Switzerland is an example of a

Particles that do not interact via the strong force but do interact via the weak nuclear force (and presumably by the much weaker gravitation force) are called

The decay n → p⁺ + e^- + γ does NOT occur because it would violate conservation of

Given that the reaction n + π⁺ → p can occur and that the quark composition of the neutron is udd and that of the proton is uud,what must be the quark composition of the π⁺ meson?

The reaction p + → e⁺ + γ is NOT possible because

If a galaxy is receding from us at 0.10c.Use Hubble's law to estimate the distance to this galaxy if the Hubble constant is 22 km/s per million light-years.(c = 3.00 × 10⁸ m/s, ,1 y = 3.156 × 10⁷ s)

The voltage across the dees of a cyclotron is 30,000 V.How many revolutions do the protons go through in reaching a kinetic energy of 21 MeV? (1 eV = 1.60 × 10^-19 J, ,m_proton = 1.67 × 10^-27 kg)

Consider the negative pion,π^-. (a)What combination of up and down quarks makes up this particle? (b)Is the π^-a baryon or a meson? (c)Is the π^- a lepton or a hadron?

Consider the decay π^o → μ^- + e⁺.This decay is

A neutral η⁰ (having mass 0.642 u) that is at rest decays into two gamma ray photons.What is the energy in MeV of each photon? (1 u = 931.5 MeV/c²)