Practice Q's Flashcards
(20 cards)
Which of the following situations would violate Newton’s First Law, assuming no force is applied? Select all that apply.
a) A falling object that has reached terminal velocity.
b) A spacecraft drifting at constant velocity in deep space.
c) A satellite steadily orbiting Earth without engines.
d) A puck sliding on ice and gradually slowing down.
e) A car making a turn at constant speed on a level road.
a, d, e
Suppose the gravitational force between two objects is initially F. How does the gravitational force change under the following changes? Select all that apply.
a) One mass doubles and the distance quadruples, the force becomes F/8.
b) The distance triples, one mass increases by a factor of 4 and the other increases by a factor of 6 and the force becomes 8F/4.
c) The distance doubles and the force becomes 2F.
d) The distance is reduced by ⅓, the force becomes 9F.
e) Both masses double and the force becomes 4F.
a, d, e
Which of the following statements is a correct pair?
a) Kepler’s Third Law: The more massive a planet, the longer its orbital period.
b) Newton’s First Law: The Earth orbits the Sun in an elliptical path with no external force acting on it.
c) Conservation of Energy: A comet’s kinetic energy increases as it falls toward the Sun, and so does the gravitational potential energy.
d) Kepler’s Second Law: A planet speeds up as it nears its star and slows down when far away from it.
e) Newton’s Second Law: If the net force on an object is zero, it accelerates at a constant rate.
d
Which of the following describe(s) how the solar thermostat regulates the Sun’s energy output?
a) The thermostat is responsible for the solar cycle and sunspots.
b) Core expansion reduces temperature, slowing fusion.
c) The thermostat maintains constant luminosity over the entire lifetime of a star.
d) Less fusion decreases pressure, allowing the core to expand.
b
Why do astronauts inside the International Space Station (ISS) appear weightless? Select all that apply.
a) Earth’s gravity is much weaker at their altitude.
b) The astronauts are constantly accelerating towards the Earth.
c) The ISS is in continuous free-fall.
d) The astronauts experience no net force.
e) The gravity of the moon and the sun balance out the gravity of Earth where the ISS is.
b, c, d
Which of the following are effects of tidal interactions? Select all that apply.
a) Tides make the volcanoes on Earth erupt.
b) The Earth’s rotation is slowing down.
c) The moon’s rotation has changed to match its orbital period.
d) The length of a day on Earth is shortening.
e) A comet plunges into Jupiter.
b, c
Assume a planet is in circular orbit around a star. Which of these statements is FALSE if you begin to increase the eccentricity of the planet’s orbit?
a) The semi-major axis will increase.
b) The planet will no longer have constant velocity throughout its orbit.
c) The distance between foci will increase.
d) The semi-minor axis will decrease.
e) The planet’s velocity at the perihelion will decrease.
e
Assume the moon’s distance to the Earth is suddenly doubled, what does this imply for tides?
a) High tides will be lower and low tides will be higher.
b) Both high and low tides will be lower.
c) High tides will be higher and low tides will be lower.
d) High and low tides will alternate faster.
a
Which of these physical laws best explains why if you jump in a train moving at constant velocity you land in the same pot.
a) Newton’s 2nd law.
b) Kepler’s 3rd law.
c) Newton’s 1st law.
d) Kepler’s 2nd law.
e) Kepler’s 1st law.
c
Imagine we were able travel from the corona into the core of the Sun, which of these phenomena would we NOT notice?
a) The density of helium atoms would increase.
b) The density of hydrogen atoms would increase.
c) The temperature would first drop before increasing again.
d) The temperature would increase throughout the whole journey.
d
what happens when the core cools?
Core cools → Fusion rate decreases → Energy output decreases → Pressure drops → Core contracts → Temperature rises
Which of the following are correct examples of the Doppler Effect? Select all that apply.
A) A ray of light looks bluer as it moves away from our telescope.
B) Music from a car sounds higher pitch as it moves towards us.
C) Light being emitted from a star coming towards Earth has less energy than when it was emitted.
D) Two stars move perpendicular to Earth; one star moves left and is redshifted; the other star moves right and is blueshifted.
E) A galaxy appears very red and is moving away from us.
b,e
Consider two identical galaxies, Galaxy A and Galaxy B. Galaxy A is moving towards Earth and Galaxy B is moving away from Earth. Which of the following statements are true? Select all that apply.
A) The energy of the light hitting the Earth will be the same since energy is conserved.
B) They are identical, so the light is emitted identically by both galaxies.
C) Galaxy A’s light will appear bluer than Galaxy B.
D) The stars in Galaxy B will appear redder than in Galaxy A.
E) Spectral lines from Galaxy B will be shifted to the redder end.
c, e
A star appears red to observers on Earth. Which of the following are potential reasons why? Select all that apply.
a) We are moving away from it.
b) It emits no light at blue wavelengths.
c) It is moving away from us.
d) It has a lower temperature than the Sun.
e) It isn’t possible to tell how a star gets its colour.
a, c, d
Which of the following happens during star formation? Select all that apply.
a) A gas cloud collapses, and temperature increases which causes energy to be lost from the cloud.
b) The density in the centre increases and photons get squeezed out to outer regions of the cloud.
c) Protostars that form begin to heat the surrounding gas and make it harder for more stars to form.
d) The outer parts of a molecular cloud are able to cool and fall into the centre.
e) The collapsed core of a molecular cloud heats up and then the collapse starts to slow down.
a, c, d, e
Which of the following is NOT something that can be determined from the spectrum of an object?
If it is obscured by dust.
Mass.
Surface Temperature.
If it is moving towards us.
Chemical composition.
mass
Suppose there is an atom with energy levels of 1eV, 2eV, 5eV, and 7eV. Which of the following is NOT possible? Select all that apply.
Absorption of a 4 eV photon
Absorption of a 1 eV photon
Emission of a 7 eV photon
Emission of a 4 eV photon
Absorption of a 7 eV photon
absorption/emission of & eV photon
The strength and/or wavelength of absorption lines on a stellar spectrum are directly determined by… (Select all that apply).
a) The motion of a star with respect to us
b) The number of protons in atoms in the core of a star
c) The energy levels of the electrons in atoms in the atmosphere of a star
d) The number atoms of a given element present in the core of a star
a, c
Which of these solar system properties is NOT a direct result of the nebular theory for the formation of the solar system?
Jovian planets exist outside the frost line.
Rocky outer planetesimals.
Terrestrial planets exist inside the frost line.
All planets orbit on the ecliptic.
The prograde motion of planets.
Rocky outer planetesimals.
Uranium-234 (U-234) is a naturally occurring isotope in rocks and soil, it decays into Thorium-230 (Th-230) with a half-life of approximately 250,000 years. Assuming you know that a rock formed 0.75 million years ago with 1 unit or U-234 and 0 units of Th-230, how many units of Th-230 would you find in the rock today?
0
1
0.25
0.5
0.875
0.875
750K/250K= 3 half lives
After 1st half-life (1 → 0.5 U-234 left, 0.5 Th-230 formed)
After 2nd: 0.5 → 0.25 U-234 left, 0.75 Th-230 formed
After 3rd: 0.25 → 0.125 U-234 left, 0.875** Th-230 formed
