Gravity & Forces
100 — What force pulls objects toward the center of a planet and keeps us on the ground?
Gravity (gravitational force).
Sun & Stars 100 — The Sun is classified as what general type of astronomical object?
The Sun is a star (specifically a main-sequence star).
Solar System Objects 100 — Which solar system object is primarily made of rock and iron, has no atmosphere, and orbits the Sun? (Name one type.)
An asteroid.
Life on Earth 100 — Name one atmospheric component essential for most life on Earth.
Oxygen (also acceptable: nitrogen, carbon dioxide depending on explanation).
Motion in Space 100 — What keeps planets in orbit around the Sun?
Gravity keeps planets in orbit around the Sun.
200 — Name Newton's law that relates net force, mass, and acceleration.
Newton’s Second Law of Motion (F = ma).
200 — Is the Sun closer to Earth than other stars, or farther? Explain briefly.
The Sun is much closer to Earth than any other star.
It appears brighter because it is the nearest star to us.
200 — What do we call small, icy bodies that develop tails when they approach the Sun?
Comets.
200 — Why is Earth's distance from the Sun important for supporting life? Use the common term for this region.
Earth lies in the Habitable Zone (or Goldilocks Zone), where temperatures allow liquid water to exist.
200 — If two planets have the same mass but one is twice as far from the Sun as the other, which one experiences a weaker gravitational pull from the Sun? (Answer: which and why, briefly.)
The planet farther from the Sun experiences a weaker gravitational pull because gravitational force decreases with increasing distance (inverse-square relationship).
300 — If a satellite orbits Earth at constant speed, what force causes it to follow a curved path instead of moving straight?
Gravitational force provides the centripetal force that keeps the satellite in a curved path.
300 — What galaxy is the Sun located in, and in which part/structure of that galaxy does it lie?
The Sun is located in the Milky Way Galaxy, in one of its spiral arms called the Orion Arm (Orion Spur).
300 — Distinguish between an asteroid and a meteor in one sentence.
An asteroid is a rocky object orbiting the Sun, while a meteor is a small fragment that enters Earth’s atmosphere and burns up.
300 — Give one reason how Earth's composition (internal or surface property) supports life.
Acceptable answers include:
Earth has liquid water.
Earth has a molten core that creates a magnetic field, protecting life from solar radiation.
Earth’s surface contains essential elements (carbon, etc.).
300 — Explain how gravity and inertia together create orbital motion.
Inertia keeps an object moving in a straight line, while gravity pulls it inward.
The combination results in a curved orbital path.
400 — Two objects: A (mass 2 kg) and B (mass 4 kg) experience the same net force. Which has the greater acceleration, and by what factor? (Explain.)
Object A (2 kg) has the greater acceleration.
Since F = ma, acceleration is inversely proportional to mass.
Because 2 kg is half of 4 kg, Object A accelerates twice as much as Object B.
400 — Explain why the Sun is described as a "medium-sized" star rather than a small or massive star (brief, conceptual).
The Sun is considered medium-sized because it is average in mass and size compared to other stars — it is larger than red dwarfs but much smaller than massive blue giants or supergiants.
400 — Name two characteristics that differentiate terrestrial planets from gas giants.
Two differences:
Terrestrial planets are rocky and dense; gas giants are mostly gas and less dense.
Terrestrial planets are smaller and closer to the Sun; gas giants are larger and farther away.
(Also acceptable: atmosphere differences, number of moons, rings.)
400 — Describe how Earth's atmosphere helps maintain conditions suitable for life (two functions).
Two functions of the atmosphere:
Regulates temperature (greenhouse effect).
Blocks harmful UV radiation.
Burns up meteoroids.
Provides essential gases for life.
(Any two earn full credit.)
400 — Describe how gravitational interactions can change the speed or direction of an object in space (give one example, e.g., gravitational assist).
Gravitational interactions can change speed or direction.
Example: A gravitational assist (slingshot maneuver) uses a planet’s gravity to increase a spacecraft’s speed and redirect its path.
500 — Describe how gravitational force changes with distance between two masses. Use the correct qualitative relationship.
Gravitational force decreases as distance increases.
More specifically: It follows an inverse-square relationship (if distance doubles, force becomes 1/4 as strong).
500 — Describe one piece of evidence astronomers use to determine the Sun’s composition.
Astronomers use spectroscopy (analysis of the Sun’s light spectrum).
Different elements absorb specific wavelengths of light, revealing the Sun’s composition (mostly hydrogen and helium).
500 — Explain what a dwarf planet is and give one example.
A dwarf planet orbits the Sun and is round but has not cleared its orbital path of other debris.
Example: Pluto (also acceptable: Eris, Haumea, Makemake, Ceres).
500 — Explain how being in the Habitable Zone and having an atmosphere work together to allow liquid water on Earth's surface.
Being in the Habitable Zone provides the correct temperature range, and the atmosphere traps enough heat and pressure to keep water in liquid form rather than freezing or evaporating.
500 — A spacecraft is coasting away from Earth. Describe qualitatively how Earth's gravitational influence on it changes as distance increases, and what that implies for thrust requirements to escape further.
As the spacecraft moves farther away, Earth’s gravitational pull decreases (inverse-square relationship).
This means less force is pulling it back, so less thrust is required to continue moving away once escape velocity is reached.