ASTRON 2B03 Midterm Exam - Multiple Choice Questions
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Questions and Answers

What happens to an atom when an electron is completely detached from it?

  • The atom is in the ground state
  • The atom is ionized (correct)
  • The atom is an isotope
  • The atom becomes part of a molecule

    • What is a requirement for an object to be considered a dwarf planet in our Solar System?

  • It must be close to a round shape (correct)
  • It must clear its orbit of other objects
  • It must be part of a larger galaxy
  • It must be a moon

    • How much smaller is the distance between the Sun and the nearest star compared to the distance between the Milky Way and Andromeda?

  • By a factor of 10 (correct)
  • By a factor of 100
  • By a factor of 1,000,000
  • By a factor of 1,000

    • Why can we study how galaxies evolve?

    <p>Because the further away we look, the further back in time we see</p> Signup and view all the answers

    What is the age of the most recent information we can get about a star 50 lightyears away?

    <p>500 years</p> Signup and view all the answers

    What are the correct standard units of mass, distance, and time?

    <p>Kilograms, meters, and seconds</p> Signup and view all the answers

    What is the duration of this examination?

    <p>50 minutes</p> Signup and view all the answers

    Where should you record your answers?

    <p>On the bubble sheet provided</p> Signup and view all the answers

    What is the consequence of arriving late to the examination?

    <p>You will be admitted to the examination room, but no extra time will be allowed</p> Signup and view all the answers

    Why must you remain silent in your seat during the last 15 minutes of the examination?

    <p>To avoid disruption to others still writing</p> Signup and view all the answers

    What is the consequence of writing on the question paper?

    <p>Your answers will not be graded</p> Signup and view all the answers

    What is the purpose of showing your student card to the exam invigilators?

    <p>To verify your identity</p> Signup and view all the answers

    What is the unit of mass commonly used in astronomy?

    <p>kg</p> Signup and view all the answers

    Why does the Solar System not expand apart due to the expansion of the universe?

    <p>The Solar System's gravity holds it together</p> Signup and view all the answers

    What is the difference in the gravitational pull of a black hole and a normal star with the same mass on a planet orbiting them at the same distance?

    <p>The two planets feel identical pulls</p> Signup and view all the answers

    What is the speed of light emitted by a spaceship moving towards you at 1/3c?

    <p>c</p> Signup and view all the answers

    How can we measure the speed at which galaxies move?

    <p>From their blueshift or redshift we can find their speed towards or away from us</p> Signup and view all the answers

    What is the implication of the universe expanding on the Solar System?

    <p>The Solar System will remain unchanged</p> Signup and view all the answers

    What would happen if we suddenly turned off gravity in the Milky Way?

    <p>Our Galaxy would fly apart</p> Signup and view all the answers

    What is the Doppler Effect?

    <p>The change in observed wavelength from a source moving relative to us</p> Signup and view all the answers

    How can we determine the distance to a galaxy that contains Cepheid variable stars?

    <p>By using the period-luminosity relation</p> Signup and view all the answers

    What happens to an object's mass as it approaches the speed of light?

    <p>It approaches infinity</p> Signup and view all the answers

    What can we conclude from the fact that all distant galaxies are redshifted?

    <p>The Universe is expanding</p> Signup and view all the answers

    Can we measure the motion of galaxies like we do for stars?

    <p>No, the speeds are too slow on human timescales to measure</p> Signup and view all the answers

    What happens to the light received from a distant star moving away from us compared to light from our Sun?

    <p>It is less energetic</p> Signup and view all the answers

    What must occur to an electron in orbit around an atom's nucleus for it to emit a photon?

    <p>It jumps to a lower energy orbit</p> Signup and view all the answers

    What is the correct order of the fundamental forces from strongest to weakest?

    <p>Strong, electromagnetic, weak, gravity</p> Signup and view all the answers

    Why do observers moving at different constant velocities see time pass at different rates?

    <p>Because time is relative to the observer's frame of reference</p> Signup and view all the answers

    What is the result of an electron jumping from a higher energy orbit to a lower energy orbit around an atom's nucleus?

    <p>A photon is emitted</p> Signup and view all the answers

    What can be said about the light emitted from our Sun and an identical distant star moving away from us?

    <p>The light from the star is less energetic</p> Signup and view all the answers

    Study Notes

    Units of Measurement

    • The correct standard units of mass, distance, and time are kg, m, and s.

    Black Holes

    • A black hole and a normal star with the same mass will exert the same gravitational pull on a planet orbiting them at the same distance.

    Speed of Light

    • The speed of light remains constant regardless of the motion of the source or observer.
    • If a spaceship moves towards you at 1/3c, the speed of the light emitted by the spaceship, as measured in your frame of reference, is c.

    Galaxies

    • The distance between the Sun and the nearest star is smaller than the distance between the Milky Way and the nearest large galaxy, Andromeda, by a factor of roughly 100,000.
    • We can study how galaxies evolve because the further away we look, the further back in time we see.

    Dwarf Planets

    • To be considered a dwarf planet, an object in our Solar System must orbit the Sun and be close to a round shape.

    Atomic Physics

    • If an electron is completely detached from an atom, the atom is ionized.
    • When an atom emits a photon and creates an emission line, one of the electrons in orbit around the atom's nucleus has to jump from a higher energy orbit to a lower energy orbit.

    Gravity

    • If gravity were suddenly turned off in the Milky Way, the galaxy would fly apart.
    • The theory of general relativity shows that gravity is not a force, but rather the curvature of spacetime.

    Relativity

    • As an object approaches the speed of light, its mass approaches infinity.
    • The theory of special relativity shows that observers moving at different constant velocities will see time pass at different rates due to the fact that everyone agrees on the speed of light.

    Stars

    • We can determine the distance to a galaxy that contains Cepheid variable stars by using the period-luminosity relation.

    Forces

    • The correct order of the fundamental forces, placing the strongest first, is strong, electromagnetic, weak, and gravity.

    Universe Expansion

    • Because all distant galaxies are redshifted, we know that the Universe is expanding.
    • If the universe is expanding, the Solar System will not eventually expand apart due to its own gravity holding it together.

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    Description

    Take this midterm exam to test your knowledge on astronomy topics, covering 30 multiple-choice questions in 50 minutes. The quiz is designed for students of Dr. Robert Cockcroft's ASTRON 2B03 course at McMaster University. Evaluate your understanding of the course material and identify areas for improvement.

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