Question 1

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. 
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 2

A galaxy is observed receding from Earth with a speed of 2800 km/s. If the Hubble constant is 22 km/s per million light-years, estimate how many years ago the light that we presently see from the galaxy actually left the galaxy. (c = 3.00 × 108 m/s, 1 ly = 9.461 × 1015 m, 1 y = 3.156 × 107 s)

Accepted Answer

A)  1.3 × 108 y 
B)  4.2 × 108 y 
C)  4.2 × 107 y 
D)  1.4 × 107 y 
E)  4.2 × 106 y 
A)  1.3 × 108 y 
B)  4.2 × 108 y 
C)  4.2 × 107 y 
D)  1.4 × 107 y 
E)  4.2 × 106 y

Question 3

The background microwave radiation, discovered in 1965 by Penzias and Wilson, has its peak intensity at a wavelength of 1.06 mm. What blackbody temperature does this wavelength imply for the universe? (σ = 5.670 × 10-8 W/m2 ∙ K4, Wien displacement law constant is 2.90 × 10-3 m ∙ K)

Accepted Answer

A)  2.7°C 
B)  -270°C 
C)  0.0027 K 
D)  0.00°C 
E)  -2.7°C 
A)  2.7°C 
B)  -270°C 
C)  0.0027 K 
D)  0.00°C 
E)  -2.7°C

Question 4

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. (c = 3.00 × 108 m/s, 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 
A)  1200 km/s 
B)  670 km/s 
C)  1500 km/s 
D)  2700 km/s 
E)  4700 km/s

Question 5

A cyclotron is designed with a magnet that produces a magnetic field of 1.2 T. When refurbished, the magnet is replaced by one that produces a 1.5-T field. How does the maximum kinetic energy achieved by the protons change compared to their previous maximum kinetic energy?

Accepted Answer

A)  It increases by 25%. 
B)  It decreases by 25%. 
C)  It increases by 56%. 
D)  It decreases by 56%. 
E)  It does not change. 
A)  It increases by 25%. 
B)  It decreases by 25%. 
C)  It increases by 56%. 
D)  It decreases by 56%. 
E)  It does not change.

Question 6

Which one of the following decays CAN occur?

Accepted Answer

A)  π+ → μ+ + vμ 
B)  p + n → p + p +   
C)  K+ → π0 
D)  μ- → e- + ve + vμ 
E)  K+ → 2π0 
A)  π+ → μ+ + vμ 
B)  p + n → p + p +   
C)  K+ → π0 
D)  μ- → e- + ve + vμ 
E)  K+ → 2π0

Question 7

What is the quark composition of the proton?

Accepted Answer

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

Question 8

The Hα spectral line of hydrogen has a wavelength of 656.3 nm as measured in the laboratory. The Hα spectral line is observed in light from a distant star at a redshifted wavelength of 789.0 nm. If Hubble's law is valid for this star, estimate how far is it from Earth 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)  2.5 × 109 ly 
B)  9.1 × 108 ly 
C)  2.7 × 108 ly 
D)  9.1 × 107 ly 
E)  2.7 × 107 ly 
A)  2.5 × 109 ly 
B)  9.1 × 108 ly 
C)  2.7 × 108 ly 
D)  9.1 × 107 ly 
E)  2.7 × 107 ly

Question 9

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

Accepted Answer

A)  positron 
B)  muon 
C)  π-meson 
D)  neutron 
E)  electron 
A)  positron 
B)  muon 
C)  π-meson 
D)  neutron 
E)  electron

Question 10

Estimate the speed of a galaxy away from us if it is 10 billion light-years from us and 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)  0.1c 
B)  0.3c 
C)  0.5c 
D)  0.7c 
E)  0.9c 
A)  0.1c 
B)  0.3c 
C)  0.5c 
D)  0.7c 
E)  0.9c

Question 11

The reaction p + e- →   + e+ 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. 
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 12

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

Question 13

Is the decay π0 → μ+ + vμ allowed?

Accepted Answer

A)  Yes, because it conserves energy. 
B)  No, because charge is not conserved. 
C)  No, because mass is created. 
D)  No, because lepton number is not conserved. 
A)  Yes, because it conserves energy. 
B)  No, because charge is not conserved. 
C)  No, because mass is created. 
D)  No, because lepton number is not conserved.

Question 14

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

Question 15

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

(a) @#IMG-DLM& d 
(b

Question 16

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. 
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 17

How many quarks are in a deuteron, 2H?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  6 
A)  1 
B)  2 
C)  3 
D)  4 
E)  6

Question 18

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. 
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 19

Composite particles that are composed of three quarks are called

Accepted Answer

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

Question 20

Suppose that the Hubble constant had the value 35.0 km/s per million light-years. (1 y = 3.156 × 107 s, mH ≈ mproton = 1.67 × 10-27 kg, c = 3.00 × 108 m/s, 1 light-year = 9.461 × 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

(a) 2.45 ×

Exam 43: Particle Physics and Cosmology

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

A galaxy is observed receding from Earth with a speed of 2800 km/s. If the Hubble constant is 22 km/s per million light-years, estimate how many years ago the light that we presently see from the galaxy actually left the galaxy. (c = 3.00 × 108 m/s, 1 ly = 9.461 × 1015 m, 1 y = 3.156 × 107 s)

The background microwave radiation, discovered in 1965 by Penzias and Wilson, has its peak intensity at a wavelength of 1.06 mm. What blackbody temperature does this wavelength imply for the universe? (σ = 5.670 × 10-8 W/m2 ∙ K4, Wien displacement law constant is 2.90 × 10-3 m ∙ K)

A cyclotron is designed with a magnet that produces a magnetic field of 1.2 T. When refurbished, the magnet is replaced by one that produces a 1.5-T field. How does the maximum kinetic energy achieved by the protons change compared to their previous maximum kinetic energy?

Which one of the following decays CAN occur?

What is the quark composition of the proton?

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

Estimate the speed of a galaxy away from us if it is 10 billion light-years from us and 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)

The reaction p + e- → + e+ is not possible because

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)

Is the decay π0 → μ+ + vμ allowed?

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

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?

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

How many quarks are in a deuteron, 2H?

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?

Composite particles that are composed of three quarks are called

Units, Physical Quantities, and Vectors

Motion Along a Straight Line

Motion in Two or Three Dimensions

Newtons Laws of Motion

Applying Newtons Laws

Work and Kinetic Energy

Potential Energy and Energy Conservation

Momentum, Impulse, and Collisions

Rotation of Rigid Bodies

Equilibrium and Elasticity

Fluid Mechanics

Gravitation

Periodic Motion

Mechanical Waves

Sound and Hearing

Temperature and Heat

Thermal Properties of Matter

The First Law of Thermodynamics

The Second Law of Thermodynamics

Electric Charge and Electric Field

Gausss Law

Electric Potential

Capacitance and Dielectrics

Current, Resistance, and Electromotive Force

Direct-Current Circuits

Magnetic Field and Magnetic Forces

Sources of Magnetic Field

Electromagnetic Induction

Inductance

Alternating Current

Electromagnetic Waves

The Nature and Propagation of Light

Geometric Optics

Interference

Diffraction

Relativity

Photons: Light Waves Behaving As Particles

Particles Behaving As Waves

Quantum Mechanics

Atomic Structure

Molecules and Condensed Matter

Nuclear Physics

Filters

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

The background microwave radiation, discovered in 1965 by Penzias and Wilson, has its peak intensity at a wavelength of 1.06 mm. What blackbody temperature does this wavelength imply for the universe? (σ = 5.670 × 10^-8 W/m² ∙ K⁴, Wien displacement law constant is 2.90 × 10^-3 m ∙ K)

Estimate the speed of a galaxy away from us if it is 10 billion light-years from us and 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)

The reaction p + e- → + e⁺ is not possible because

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)

Is the decay π⁰ → μ⁺ + v_μ allowed?

How many quarks are in a deuteron, ²H?