Questions and Answers
The Earth moves faster than other ______ in the celestial sphere.
planets
______ could not explain the existence of stellar parallax due to the vast distances of stars.
The geocentric model
Tycho Brahe observed ______ on the moon, indicating it is not a perfect sphere.
craters
Johannes Kepler developed laws that described ______ motion in a simplified manner.
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Isaac Newton’s contributions included ______, optics, and laws of motion.
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Kepler introduced the terms perihelion and ______ in relation to a planet's orbit around the sun.
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Tycho Brahe cataloged thousands of stars with precision before the ______ was invented.
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One concern with heliocentrism is that we do not ______ the motion 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 of Cnidus created the first model of a ______ Universe.
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In Eudoxus' model, the orbits of celestial bodies were described as ______.
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Aristarchus of Samos proposed a ______ model where Earth and planets orbit a fixed sun.
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The apparent shift of an object with respect to the background is referred to as ______ parallax.
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Inferior planets include ______ and Venus.
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Eudoxus' model had problems, including changes in the brightness of ______.
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Copernicus stated that planets have uniform circular orbits around the ______.
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The orbits are ______
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A body at ______ will remain at rest
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Planets cover equal areas in ______ time
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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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Third Law: Law of Action and ______
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The force exerted by object 1 upon object 2 is equal in magnitude and ______ in direction
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If r decreases, attraction will ______
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Henry Cavendish proved the value of G = 6.67 x 10-11 N m²/kg², which is known as the gravitational ______.
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In physics, a ______ is defined as a quantity with magnitude only, lacking direction.
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In contrast, a ______ has both magnitude and direction.
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According to Newton's laws, when an elevator is not in motion, the weight is ______.
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During upward acceleration in an elevator, the apparent weight becomes ______.
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When accelerating downwards in an elevator, the apparent weight is ______.
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In free-fall, individuals experience ______, meaning they feel no weight due to the lack of support force.
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The formula for force according to Newton's second law is ______ = mass × acceleration.
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Albert Einstein challenged Newton's picture of universal ______.
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In swimming, one must push the fluid ______ to swim forward.
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General relativity explains the physics of all ______.
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A ______ is an educated guess, offering a minimal explanation of a phenomenon.
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In quantum mechanics, an observer can detect the position or ______ of a quantum principle, but not both at the same time.
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Study Notes
Retrograde Motion and Celestial Models
- Retrograde motion refers to the apparent change in direction of Mars due to differences in orbital speeds.
- Eudoxus of Cnidus created the first Geocentric model with circular orbits where celestial bodies were fixed.
- Problems with Eudoxus’ model included the changing brightness of planets and the non-uniform motion of the Moon and Sun.
- Aristarchus of Samos proposed the Heliocentric model, placing the Sun at the center with circular orbits for planets and the Moon around Earth.
- Stellar parallax describes the apparent shift of an object against a distant background, supporting heliocentrism.
Key Astronomers and Contributions
- Claudius Ptolemy enhanced the Geocentric model but failed to explain various celestial phenomena.
- Tycho Brahe made detailed observations such as moon craters and the phases of Venus, challenging prior beliefs about celestial perfection.
- Johannes Kepler introduced elliptic planetary orbits and formulated three laws of planetary motion.
- Isaac Newton contributed to physics with calculus, optics, and formulated his laws of motion and universal gravitation.
Newton's Laws of Motion
- Law of Inertia: An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.
- Law of Acceleration: Force equals mass times acceleration (( F = m \times a )). Acceleration is directly proportional to force and inversely to mass.
- Law of Action and Reaction: For every action, there is an equal and opposite reaction.
Universal Gravitation
- Newton's Universal Law of Gravitation states that the force of attraction between two objects is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
- Value of gravitational constant ( G = 6.67 \times 10^{-11} , N \cdot m^2/kg^2 ).
Vectors vs. Scalars
- Scalars have magnitude only (e.g., temperature), while vectors have both magnitude and direction (e.g., velocity).
- Applications of Newton's laws include real-life scenarios like elevators and the behavior of fluids.
Einstein’s Theory of Relativity
- Albert Einstein challenged Newton’s views, proposing that gravity is the distortion of space caused by mass.
- Special Relativity focuses on how observers perceive physical effects due to relative velocity; General Relativity pertains to the physics of gravity in all contexts.
Scientific Concepts
- A hypothesis is an educated guess, while a fact is a proven observation.
- Theories explain why phenomena occur, while laws describe what happens based on repeated observations.
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Description
Explore the fascinating phenomenon of retrograde motion in Mars as covered in Science 10. This quiz delves into the ideas presented by ancient astronomers like Eudoxus and explains how the apparent change in Mars' direction occurs. Test your understanding of this important concept in astronomy!
