Questions and Answers
The orbits are ______
ellipses
A body at rest will remain at rest, and a body in motion will remain in ______
motion
Planets cover equal areas in equal ______
time
A planet’s orbital period is proportional to the size of its ______
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The acceleration of the object is directly proportional to the ______
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The higher mass, the more ______
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The force exerted by object 1 upon object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 upon ______
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If the distance ______ decreases, attraction will increase.
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Henry Cavendish proved the value of G = 6.67 x 10-11 N m²/kg², which is known as the universal ______.
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In physics, a ______ is described as having both magnitude and direction.
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According to the law of ______, an object in motion stays in motion unless acted upon by an external force.
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In an elevator that is accelerating upward, the perceived ______ will be greater than normal.
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EINSTEIN’S THEORY OF ______ challenged Newton’s picture of universal gravitation.
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According to Einstein, gravity is not a force but rather an effect; a distortion in the shape of ______ due to mass.
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The formula for calculating force is ______ = mass × acceleration.
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The distinction between a hypothesis, a theory, and a ______ is important in scientific discourse.
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During free-fall, an object experiences ______, resulting in a sensation of zero weight.
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Examples of ______ include displacement, velocity, acceleration, and force.
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In special relativity, the effects are compared from different observer positions in terms of ______ or speed in a particular direction.
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In case 3 of the elevator dilemma, when going down, the weight experienced is ______.
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Swimming involves pushing the fluid ______ to swim forward.
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The celestial ______ has a perfect shape.
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Tycho Brahe observed the ______ of Jupiter, demonstrating that they are not unique to Earth.
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Kepler developed simple laws that accounted for ______ observations.
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Newton introduced the terms perihelion and ______ in relation to planetary orbits.
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Johannes Kepler's first law states that planets move in ______ orbits around the sun.
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Stellar parallax is not observable because stars are ______ away.
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Isaac Newton's contributions include calculus, optics, and the laws of ______.
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In heliocentrism concerns, it was noted that we do not feel the ______ of the Earth.
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The apparent change in the direction of the motion of Mars is known as ______ motion.
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Eudoxus created the first model of a ______ Universe.
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Eudoxus' model included concentric circles called ______.
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Small circles with centers that move along the deferent are known as ______.
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The Heliocentric Model was proposed by ______ of Samos.
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According to Copernicus, planets have uniform circular orbits around the ______.
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Inferior Planets include ______ and Venus.
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Superior Planets consist of Mars, Jupiter, and ______.
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Study Notes
Retrograde Motion and Early Models
- Retrograde motion of Mars is the apparent backward movement due to the differing speeds of Earth and Mars.
- Eudoxus of Cnidus proposed the first geocentric model, asserting that celestial bodies travel in uniform circular orbits around Earth.
- His model included concentric circles (deferents), small circles (epicycles), and an imaginary point called equant for motion variations.
- He noted changes in brightness and size of celestial bodies but could not reconcile these with his model.
Heliocentric Model
- Aristarchus of Samos introduced the heliocentric model with Earth and planets orbiting a fixed Sun, proposing that the Moon orbits Earth.
- Stellar parallax reflects the apparent shift of distant objects due to Earth's motion.
- Nicolaus Copernicus refined the heliocentric theory, emphasizing uniform circular orbits around the Sun, with Earth at a faster orbital speed leading to retrograde motion.
Important Contributions from Astronomers
- Claudius Ptolemy enhanced the geocentric model but failed to explain retrograde motion satisfactorily and could not observe stellar parallax due to distance.
- Tycho Brahe conducted precise astronomical observations before telescopes, discovering lunar craters, sunspots, moons of Jupiter, and phases of Venus, implying a broader view of the cosmos.
- Johannes Kepler formulated three laws of planetary motion, providing evidence for elliptical orbits and relationships between a planet's distance from the Sun and its orbital period.
Newton's Fundamental Laws and Gravitation
- Isaac Newton introduced laws of motion and universal gravitation, explaining gravitational forces as proportional to masses and inversely proportional to the square of the distance between objects.
- He defined key terms such as perihelion (closest point to the Sun) and aphelion (farthest point), clarifying planetary movements.
Laws of Motion
- Newton's First Law (Law of Inertia): An object remains at rest or in uniform motion unless acted upon by a net external force.
- Newton's Second Law (Law of Acceleration): Force equals mass times acceleration (F=ma), demonstrating the relationship between force, mass, and acceleration.
- Newton's Third Law (Law of Action and Reaction): For every action, there is an equal and opposite reaction; forces between two objects are equal in magnitude and opposite in direction.
Vectors and Scalars
- Scalars are quantities with magnitude only, whereas vectors have both magnitude and direction.
- Examples of vectors include velocity, acceleration, and force.
Einstein’s Relativity
- Albert Einstein challenged Newton's gravitational framework with his theory of relativity.
- Special relativity analyzes physical effects from different observers' perspectives regarding speed and direction.
- General relativity describes gravity as the curvature of space caused by mass, rather than a traditional force.
Definitions of Scientific Concepts
- Hypothesis: An educated guess or preliminary explanation of phenomena.
- Law: A statement describing what happens under specific conditions based on repeated trials.
- Theory: A well-substantiated explanation of certain phenomena, providing insights into why events occur.
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Description
This quiz covers the concept of retrograde motion specifically related to Mars. It explains the phenomena where Mars appears to change its direction due to differences in motion relative to Earth. Ideal for students studying the physical world in science class.
