Physics 10 Reviewer PDF

PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Lesson 1 - Initial Remarks on Science and Physics o Occam’s Raz...

PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Lesson 1 - Initial Remarks on Science and Physics o Occam’s Razor: The simplest explanation is usually the best Visitors From Twilo - Mensuration - Taken from Leon Lederman’s “The God Particle” o If something can be properly measured - Imagine an intelligent race of beings from the using universally accepted scales, planet Twilo. generalizations about it are rendered - They look more or less like us, they talk like us, unambiguous they do everything like humans - except for one o Consider process of observation with thing, they can’t see objects with a sharp human senses, it really creates a mental juxtaposition of black and white model of the real world, as macroscopic - A contingent from Twilo comes to Earth on a approximation to the microscopically goodwill mission comprised real world. Therefore absolute - We take them to see one of the most popular reliance on perceived fact are subject to cultural events on the planet: error induced by crudeness of model Twiloans Try to Make Sense of Soccer - Heuristics - Young Pipsqueak Twiloan: “Let's postulate the o The best science stimulates further existence of an invisible ball.” discovery, often in unpredictable new directions, and the new knowledge - Elders: Say what? - How did the pipsqueak come up with the idea? provides an additional test of the original principles that led to the discovery - Consilience o The explanations of physical phenomena most likely to survive are those that can be connected and proved consistent with one another Planet Neptune’s existence was predicted by Skill Sets Urbain Le Verrier this way! Perspective/Open-mindedness Science is thinking beyond, out of, and of the Diagnostic Features of Science “box” - Repeatability Example: Heliocentrism VS Geocentrism o The same phenomenon is sought again Sense Making and again, preferably by independent Science is not just accumulating facts but investigation, and the interpretation putting them together in a coherent way given to it is confirmed or discarded by Example: existence of atoms means of novel analysis and Ability to Falsify experimentation. Karl Popper: “It is easy to obtain - Economy confirmations, or verifications, for nearly o Scientists attempt to abstract the every theory — if we look for confirmations. information into the form that is both simplest and most pleasing - the “Every genuine test of a theory is an attempt combination called elegance - while to falsify it, or to refute it. Testability is yielding the largest amount of information falsifiability...” with the least amount of effort Example: Phlogiston theory  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 PHYSICS 6. You can’t predict or know everything (Quantum Theory And The End Of From the Greek word “phusis” (sometimes Causality) “physis”) which means nature 7. Fundamentally, things never change Physics is difficult to define since the subject (Conservation Principles And Symmetry) has been evolving Instead of trying to define physics, we Lesson 2 - The Greeks and The Homocentric attempt to characterize it instead Model Characterizing Physics Goals – To understand nature, that is, Greeks, Matter, Motion, and the Universe rationalize, explain and predict physical phenomena Natural Philosophy and the Role of Mathematics Strategy – Use of abstraction or unifying concepts (e.g. energy, entropy, charge, force, Greece 7th Century B.C. etc.) The Universe is a rational place, with natural Tools – Mathematical models, experiments, laws that can be figured out. computational work Subfields – Up to the 19th Century: Natural Philosophy Astronomy, Mechanics, Acoustics, Fluid An attempt to develop a consistent set of “natural Mechanics, Electromagnetism, Optics, laws” to explain physical phenomena without Thermodynamics, Statistical Physics – reference to supernatural causes / beings. Modern Physics: Relativity, Cosmology, Astrophysics, Quantum Mechanics, High Energy Physics, Condensed Matter Physics, Chaos, Nonlinear Dynamics, Complex Systems, Biological Physics, Earth Systems Physics Physics is about Frontiers! – Dark Matter, M- Theory, Quantum Computing, etc. 7 Important Ideas in Physics 1. The Earth is not the center of the universe (Copernican Astronomy) 2. The universe is a mechanism run by rules (Newtonian Mechanics And Causality) Pythagoras 3. Energy is what makes it go (The Concept Of 1 – represented reason, for reason could produce Energy) only one consistent body of truth 4. Entropy tells it where to go (Entropy And 2 – stood for man Probability) 3 – stood for woman 5. The facts are relative but the law is absolute 4 – symbol for justice, being the first number that (Relativity) is the product of two equals 5 – identified with marriage, because it is formed by the union of 2 and 3 PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Greeks guided by a paradigm first articulated by Pythagoras (c569--475 B.C.E) before Socrates' time. Key points about the movements of celestial objects: 1) The planets, Sun, Moon and stars move in perfectly circular orbits. 2) The speed of the planets, Sun, Moon and stars in their circular orbits is perfectly uniform. 3) The Earth is at the exact center of the motion of the celestial bodies. Some Things that the Greeks Got Right 1. Diurnal and Annual Motion 2. Hipparchus: precession of the equinoxes, systematic recording of observational astronomy 3. Earth is spherical 4. Eratosthenes: Good estimate for the size of the Earth 5. Time between 1st Quarter and Last Quarter not the same as time between Last Quarter and 1st Quarter 6. Retrograde Motion How do we reconcile the Pythagorean paradigm with the observed motion of the heavenly bodies ? Plato: “Allegory of the Cave” Plato: “Saving the Appearances” Observed motion = combinations of uniform circular motion  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Task for future Philosophers: Explain the Moon:1+2 observed motion of the heavenly bodies in terms Sun:1+2 of combinations of uniform circular motions. Venus:1+3 Mercury:1+3 Greek View of the Universe Mars :1+3 Jupiter:1+3 Saturn:1+3 Geocentric theory of the universe “Earth- Stars: 1 centered universe” TOTAL: 27 SPHERES Early Greek Universe : Earth + celestial spheres (Eudoxus, Aristotle) Aristotle’s Model Problem with Eudoxus: “Intelligences” etc. Introduced: Prime Mover + 28 other spheres (gear-like mechanism) Problems with Aristotle’s Model Can’t Explain: o Change in apparent size of moon o Change in brightness of the planets Greek View of the Universe Geocentric theory of the universe “Earth-centered universe” Eudoxus (Homocentric Model) Early Greek Universe: Earth + celestial spheres (Eudoxus, Aristotle) Ptolemy’s Universe: Additional devices to account for actual observations. [Details next meeting] Minority View: Aristarchus (310-230 B.C., Greek) the Sun is in the center of the universe theory considered too radical note that he was 1,750 years ahead of Copernicus Quiz: In the Pythagorean system of numbers, 5 stood for marriage. Using a single word, what do you think the number 6 stood for? Briefly explain why.  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 In the Pythagorean system, the number 6 stood for Eccentric "harmony." Equant This is because 6 is considered a "perfect number" in mathematics, being the sum of its divisors (1, 2, and 3), and symbolizes balance and proportion. In Pythagorean philosophy, harmony reflected balance in life and the cosmos. Lesson 3 - The Fall of Geocentric Theory and The Rise of Heliocentric Theory Ptolemy’Geocentric Model Ptolemy’s Calculational Devices Deferent Epicycle As a planet moves around on its epicycle, the center of the epicycle (called the “deferent'') moves around the Earth. When its motion brings it inside the deferent circle, the planet undergoes retrograde motion.  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 COPERNICUS and the Heliocentric Model of the Universe Theological / Philosophical Grounds Against the Model The Earth should be different from other planets since it should be in a special place in the universe (Giordano Bruno’s “heresies”). o Other planets will not be perfect o Other “earthly beings” must exist Heliocentric model would lead to Sun worship. Physical Grounds Against the Model 1. Stellar parallax is not observed since constellations do not disarrange. COPERNICAN MODEL version 1 vs. version 2 2. Apparent size of stars does not change 3. Violated expectations of the Aristotelian physics prevalent in his time: a. Breeze at thousands of miles per hour b. Falling motion should not be simpler c. Spinning earth would fly apart  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 d. Unimaginable amount of force would 4. Removed the necessity of crystalline celestial spheres be required to keep Earth moving Apologetic Response for Copernican Model TYCHONIC MODEL Useful for calculations Not necessarily connected with reality Tychonic system appeals to both the homocentric principle and the heliocentric revolution of other planets. Strange hybrid of geocentrism and heliocentrism Earth was at center Increased support for research Sun orbits earth Planets orbit sun Impressed by Tycho’s observation in 1572, construction of research facilities was financed by King Frederick II Laws Of Planetary Motion (Denmark and Norway) and later emperor Rudolf II Brahe died without having confirmed the validity (Roman Empire). of his model. Kepler inherited vast amount of data. Tycho Brahe (1546 - 1601) Trial And Error Fits Lead to Laws Of Planetary Motion Copernican and Tychonic models do not fit. Greatest naked-eye astronomer Introduced new heliocentric models but none Proved that comets were fitted. celestial objects It took 20 years to eventually end up with an Proved that a supernova was a empirical model… celestial object Kepler’s Three Laws of Planetary Motion 1. Law of orbit. Planets orbit the sun in elliptical Significant Contributions of Tycho Brahe orbits with the sun at one of the focii. 2. Law of equal areas. The line joining a planet, and 1. Discovery of a “nova stella” – Not due to earth’s the sun sweeps equal areas at equal times. atmosphere (no parallax) – Stars are not eternal 3. Law of period. The square of the period of a 2. Accurate astronomical data for his time – Stellar and planet’s revolution is directly proportional to the planetary positions – Better measure of earth’s axial cube of its average distance from the sun. tilt – Anomalies in Ptolemaic model surfaced 3. Proved that comets are celestial objects  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Erasing Theological Doubts QUIZ Briefly explain how the Aristotelian/Eudoxan, Ptolemaic, Galileo Galilei (1564-1641) and Copernican explanations of retrograde motion differ. - Improved early telescope designs Ans. The Aristotelian/Eudoxan model explained - Made many observations retrograde motion with complex spheres around Earth. of heavenly bodies. The Ptolemaic model used small circular orbits (epicycles) to make planets appear to move backward. The Copernican model, which placed the Sun at the Galileo’s Astronomical Observations center, explained retrograde as an illusion when Earth Craters of the moon overtakes a slower-moving planet. Sunspots Saturn’s rings Moons of Jupiter Lesson 4 - Aristotelian Physics and Galilean Phases of Venus Mechanics Unchanging size of stars (indication of their vast distance) Aristotle & Greek Thought Ptolemy’s Model Cannot Copernican Model’s Aristotle’s scientific system influenced Explain Elegant Explanation medieval Christian and Islamic thought Venus is always between Venus can travel behind until the late 17th century. earth and sun the sun Despite later intellectual revolutions, Publication of Arguments Aristotelian ideas stayed rooted in Western thought. Dialogue Concerning the Two Chief World His work was the first to describe the Systems (Dialogo) physical universe using logical arguments o Conviction of “grave suspicion of based on basic assumptions. heresy” Aristotelian ideas dominated for 2000 o Disguised as “Dialogue on the Tides” years. Characters: o Salviati – Copernican position (name of friend) Aristotelian Physics o Sagredo – intelligent layman, neutral Types of motion (name of friend) o Celestial o Simplicio – Ptolemy and Aristotle’s o Alteration position Discourse lasted four days o Natural o Violent Needed final touch up of the model Aristotle and the Four Elements Kepler’s laws are empirical laws: model is fitted o Fire to the data. o Wind Needs a physical theory that supports the current o Water model. o Earth  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Violent Motion o Falling motion is uniform motion Motion caused by an external force (constant speed). Once an arrow is released, how does it keep on Horizontal Motion moving? o An impetus is required to sustain Antiperistasis! motion. Projectile Motion Aristotle’s Laws of Motion o Two mechanisms for projectile First Law motion o The speed of falling is proportional to the weight of the object. Heavier Motion according to Galileo things fall faster. Falling Motion o Falling is independent of weight. Second Law o Falling is uniformly accelerated. o The speed by which an object falls Horizontal Motion depends inversely on the density of o To sustain motion, no force is needed the medium it is falling through. o Force is only required to change motion, not sustain it. Additional Notes: In violent motion, the Projectile Motion speed of the object is proportional to the o Projectile motion is a superposition of applied force vertical and horizontal motion Aristotle asserted that during violent motion the speed of the object is directly proportional to the applied force. Status of Heliocentric vs. Geocentric Debate after Galileo’s Studies in Mechanics Why did Aristotelian Physics prevail? The power of theory and abstraction Aristotelian Physics is wrong Manual work is not for free citizens Galileo: Horizontal motion = circular motion Experiment was not easy to conduct in ancient times Additional notes on Galileo Galileo was often right but was sometimes Galileo vs. Aristotle wrong e.g. Aristotle: LOGIC is the best test of knowledge o Ignored Kepler and his elliptical Galileo: EXPERIMENT is the best test of orbits knowledge o Insisted on circular motion o Wrong explanation of tides Status of Heliocentric vs. Geocentric Debate after Galileo, Brahe & Kepler’s contributions (~ca Motion according to Aristotle 1609- 1619) Falling Motion Ptolemaic Model abandoned o Object’s fall at a rate proportional to their weight Tychonic vs. Copernican ▪ Heavy objects fall faster than Objections based on Aristotelian physics not light objects yet addressed by Copernican Model  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Kepler’s 1st and 2nd Laws of planetary Velocity – rate of change of position, plus a motion (1609) direction Kepler’s 3rd Law of planetary motion (1619) Acceleration – rate of change of velocity Our Model of the Universe (ca 1642) Free-Body Diagrams Better data Tycho Brahe Used to show the relative magnitude and Final touch-up of the model Johannes Kepler direction of all forces acting on the body in a Promotion of the new mode Galileo Galilei given situation Decide which body you are referring to Still missing someone to put the pieces together to Draw only forces acting on the body form a coherent physical theory in the modern sense Newton’s First Law – [Law of Inertia] Quiz A body at rest w/ zero net force remains at Using Aristotelian physics, briefly explain why a rest sheet of paper riddled with holes falls faster than a A body in motion keeps moving if there is sheet of paper without holes zero net force acting on it “A body acted on by no net force moves with Ans. In Aristotelian physics, objects fall based on constant velocity (which may be zero) and their nature and interaction with the medium (air). A zero acceleration.” sheet of paper with holes has less resistance from the Ex. Ketchup bottle, trains, shaking wet hand, etc. air because the holes allow air to pass through more “The vis insita, or innate force of matter, is a power of easily. As a result, it encounters less opposition and resisting, by which every body, as much as in it lies, falls faster than a solid sheet, which has more surface continues in its present state, whether it be of rest, or of area for the air to push against. moving uniformly forwards in a right line.” Lesson 5 - Newtonian Physics and the 3 Laws of “A body, from its inert nature of matter, is not without Motion difficulty put out of its state of motion. Upon which account, this vis insita may, by a most significant name, be called inertia (vis inertiae) or force of inactivity.” Sir Isaac Newton Formulated the laws of motion based on What happens when we push an object? experimental observations The more force….The more acceleration “Qui genus humanum ingenio superavit” The bigger the object, the lesser it accelerates. It moves in the direction of the force. Terminologies Vector – a quantity with magnitude and Newton’s 2nd Law – Law of Acceleration direction “If a net external force acts on a body, the body Force – In a simplest sense, a push or a pull. accelerates. The direction of acceleration is the Its source may be gravitational, electrical, same as the direction of the net force. The mass of the body times the acceleration equals the net magnetic or simply muscular effort force vector.” [measured in NEWTONS] 𝐹 = 𝑚𝑎 Net Force – a (vectorial) sum of all forces A non-zero net force causes acceleration  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Mass Versus Weight 3rd Law in Action! Mass – The quantity of matter in an object. It is Cannon and Cannonball also the measure of inertia or sluggishness that an Bug versus Windshield object exhibits in response to any effort made to start it, stop it, or change its state of motion in any way Lesson 6 - Universal Law of Gravitation & Weight – The force upon an object due to gravity Newtonian Synthesis Free Fall near earth’s surface Center of Mass (Center of Gravity) only gravity is acting Average position of all the mass that makes includes objects thrown upwards up the body constant acceleration with magnitude g = 9.8 Center of mass obeys Newton’s laws m/s2 Uniform Circular Motion Keeps on changing direction -> must be Locating the Center of Mass accelerating! Center of mass can be outside the body! The force causing the acceleration is known as the centripetal force Stability & Tipping Inside the can, a bug feels the centripetal force as Stability is determined by the vertical well (can pushes on her feet) distance the center of mass is raised in tipping An object with a wide base and a low center of mass is more stable From the point of view of the bug, she is at rest, hence, the centripetal force must be countered by Moon and It’s Orbit a centrifugal force The tangential velocity of the moon about the earth allows it to fall around the earth rather Observation leading to 3rd Law than directly into it When the hammer exerts a force on the stake, it is brought to a halt in the process Law of Gravitation “Every particle of matter in the universe attracts every Newton’s 3rd Law - Action & Reaction other particle with a force directly proportional to the “If body A exerts a force on body B (an “action”), product of the masses of the particles and inversely then body B exerts a force on body A (a proportional to the square of the distance between them.” “reaction”). These two forces have the same 𝐺𝑚1 𝑚2 magnitude but are opposite in direction. These two 𝐹𝑔 = forces act on different bodies.” 𝑟2 Action-reaction pair acts on different bodies. This is why punching the floor hurts your hand, G = 6.67 x 10-11 Nm2/kg2 (Gravitational Constant) and why people wear gloves in boxing. Earth acts on falling objects (this force being the weight of the object) at the same time, the object pulls on Earth with exactly the same magnitude  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Universal Gravitational Constant G Just as π relates circumference and diameter for circles, G relates force with mass and distance First obtained by Henri Cavendish Ocean Tides Caused by the differences in the gravitational pull between the moon and the earth on opposite sides of the earth The sun gravitational pull on the earth is 180 times that of the moon. Why doesn’t the sun cause 180 times greater than lunar tides? Spring Tide vs. Neap Tide Spring Tide – higher-than-average high tides and lower-than-average low tides Neap Tide – lower-than-average high tide and higher-than-average low tide Planetary Motions and The Center of Mass Gravity & the Model of the Solar System Why is the sun the center of the solar system?  PHYSICS 10 – THX-3 2:30 PM – 4:00 PM NIP LP101 First Semester, A.Y. 2024-2025 Ans. The fingers meet at the center because of unequal friction. The finger with less weight slides first, while the one with more weight stays put due to higher friction. As this process alternates, both fingers eventually meet at the center of mass, where the stick is perfectly balanced. Newtonian Synthesis During the time of Aristotle, bodies on earth are one of 4 elements while bodies on heaven are made of the 5th element known as the “quintessence”. Due to the Newtonian synthesis, we learned that the motion of bodies in heaven obeys the same laws of motion as do bodies on earth. Quiz A person balances a meterstick on a horizontal position on the extended index finger of both hands. That person slowly brings the two fingers together. The stick remains balanced and the two fingers ALWAYS meet at the 50-cm mark (which in this case is the center of mass of the meterstick) regardless of their original positions. Explain this mind-blowing phenomenon using everything you know.