AP2 Unit 7 MCQ Review

An unstable atom of uranium-238 of mass mv at rest decays into thorium-234 of mass mTh... what equation should the student used to represent the conservation of energy, and how is the use of this equation justified?

(mU-mTh-mHe)c^2= 1/2(mTh)(vTh^2) + 1/2(mHe)(vHe^2)

The figure shows the energy levels of a hypothetical single-electron atom... which of the following indicate a possible frequency of a photom emitted by the atom during this process? Select two answers.

1. 4.83 x 10^14 Hz 2. 1.45 x 10^15 Hz

Particles called muons are produced high in Earth's atmosphere and move at high speeds... which of the following descriptions of muon behavior provides a reason for refining classical physics in some situations? Select two answers.

1. The muons experience time different due to their high speeds... 2. The distance from the upper atmosphere to Earth is different in the muons' frame of reference...

The figure shows the energy level diagram for a hypothetical single-electron atom. If the atom is in the first excited (n=2) state, photons with which of the following energies could be absorbed by the atom?

1.5 eV

A proton fused with a C13 nucleus and produces a N14 nucleus and a gamma ray, as shown in the equation. What is the approximate frequency of the gamma ray?

1.85 x 10^21 Hz

The Sun emits energy in the form of light at a rate of approximately 10^26 W... which of the following represents the approximate fraction of the Sun's mass in its core?

10%

In a hypothetical nuclear decay process for an atom, the mass of one proton is transformed into energy? Which option gives the best estimate for the amount of energy released in the process?

10^-10 J

What is the mass of an object that has a rest energy of 1.69 x 10^36 eV?

3.00 kg

A 211A95 nucleus with mass 241.056829 u undergoes spontaneous alpha decay... the energy released in the decay reaction is most nearly

6.65665 MeV

Two isotopes of hydrogen at rest are fused to form helium, a neutron, and an unknown number of gamma rays, as shown in the reaction. The number of gamma rays emitted during the fusion process is most nearly

71

The energies of the first five energy levels of hydrogen are shown... which of the following gives a correct description of an electron transition in hydrogren?

A red photon is emitted when the electron transitions from level 3 to level 2

In the early 1900s... which of the following reasons could provide evidence to support the proposed theory?

After the decay of certain unstable nuclei... converted into a particle that was originally not accounted for.

When considering interactions between macroscopic objects, physicists apply conservation of mass. When considering interactions between nuclei, physicists apply conservation of mass-energy. Which of the following describes a reason why?

During nuclear reactions, a nonnegligible amount of mass can be converted to other forms of energy

Which of the following correctly describes the nuclear force that holds the protons of a boron nucleus together?

It is stronger than the electric repulsion at small distance scales

Which of the following facts does NOT provide direct support for the theory of the conservation of mass-energy?

Larger atoms have more neutrons

Carbon-14 decays into nitrogen-14 through a process called beta minus decay... which of the following gives the best interpretation of this result and a justification?

Mass alone is not conserved in the decay but mass-energy is conserved. The KE of the decay products is delta mc^2 greater than that of the reactants.

An electrically neutral, unstable atom of carbon-14 decays to form a nitrogen atom, an antoneutrino, and a third particle X... which of the following predictions are correct about the mass number and charge number of the missing particle X?

Mass number: 0 Charge number: -1

A proton of mass mp has a speed of 1000 m/s when it collides head-on and elastically with an alpha particle of mass 4mp that is at rest... which of the following contains equations that result from correctly applying momentum and KE to the situation...?

Momentum: 1000= vp+4va Energy: 1000^2= vp^2 + 4va^2

The figure shows the energy level diagram for a hypothetical single-electron atom. In a simplistic model of a single electron orbiting a nucleus, the possible orbits of the electron have circumferences that are integer multiples of the de Broglie wavelength of the electron. Which of the following is a consequence of this model?

Single-electron atoms absorb photons with only specific, discrete energies

Which of the following phenomena can be explained by the model of discrete atomic energy levels in the hydrogen atom?

Spectral absorption lines

A photon spontaneously transforms into an electron-positron pair. Which of the following claims is correct about the internal energy of the electron-positron system?

The energy of the photon is equal to the sum of the KE and rest mass energies of both the electron and positron

Two alpha particles exert repulsive forces on each other... which of the following statements explains why the configuration is stable?

The force between nucleons have nonnegiligible magnitude over small distance scales...

Two electrons are launched toward each other with equal kinetic energies of 25 eV. Which of the following predictions is correct about the internal energy of the two-electron system as they interact?

The internal energy of the electron-electron system always stays at 50 eV as the electrons slow down to a stop and then speed up again.

Which of the following describes the change in the nucleus of an atom that undergoes B- decay?

The number of proton increased by 1, and the number of neutrons decreases by 1

In deep space, a 10,000 kg space vehicle... in the context of this astronaut scenario, what makes this revision necessary?

The relative speed of Astronaut 2 and the vehicle

Observer 1 is stationary. Observer 2 is traveling on a spaceship at a relativistic speed and passes Observer 1. Which of the following quantities, if any, will be the same for both Observer 1 and Observer 2?

The speed of the laser light through the air in the spaceship

In a fission reaction, a U-235 nucleus decays into krypton and barium nuclei and 3 neutrons... what is the total mass of the products and why?

The total mass of the products is less than 236.0526 u because some mass is converted to energy and released in the reaction. The total amount of mass plus energy of the system is conserved.

A 10C6 nucleus decays into a 10B5 nucleus, a neutrino, and a positron. Which of the following correctly describes a similarity between the neutrino and the positron?

They are both fundamental particles with no known substructure

A 10C6 nucleus decays into a 10B5 nucleus, a neutrino, and a positron. Which property is conserved during the decay?

Total charge

A hydrogen atom is in an excited state. According to the standing wave model of the atom, when the atom emits a photon its energy

decreases and the electron moves closer to the nucleus

Classical physics predicts that the mass of the deuterium nucleus- the fusion of a proton and a neutron- would be the sum of the proton mass and the neutron mass. Which of the following represents the mass defect delta m of the fusion reaction and a method of how to determine the binding energy Eb?

delta m= 2.2 MeV/c^2 How to determine Eb= Eb is the product of delta m and c^2

In nuclear beta decay, a neutron of mass mn at rest decays in to a proton of mass mp, an electron of mass me, and a neutrino of negligible mass. Which of the following expressions is equivalent to the energy released by this reaction?

mnc^2- (mp + me)c^2

A neutron with mass mn moves with speed vn and collides with a uranium-235 nucleus with mass Mu that is at rest... which of the following represents an equation that can be used to calculate the speed of the uranium nucleus immediately after the neutron is absorbed?

mnvn= (mn + Mu)vt, because the uranium atom abosrbs the neutron, and momentum is conserved in an inelastic collision

The figure shows the energy level diagram for a hypothetical single-electron atom. The atom is later in the n=4 state. It then transitions to a lower energy state. A transition to which state would result in the emission of a photon with the longest wavelength?

n=3

Proton A, moving to the right with velocity v, collides with proton B, initially at rest. If the wavelength of proton A if lamda A before the collision, what is the wavelength of proton A after the collision?

root(2*lamdaA)

A proton traveling with velocity vA1 strikes a proton that is initally at rest... which of the following contains the equations needed to determine whether the collision is elastic and justifies their use?

vA1^2= vA2^2+vB2^2 is the only equation needed, because the collision is elastic if energy is conserved