Physics Final Study Guide PacketPhysics Final Review Part I: Nucleus & Earth's Engine Name: Date: The Battle for the Nucleus The Strong Force (attractive, short-range) and Electrical Repulsive Force (pushing protons apart, long-range) compete. Large nuclei decay when the Strong Force can't hold the distant protons. Half-Life Logic Half-life is constant. 1 HL = 1/2 left, 2 HL = 1/4 left, 3 HL = 1/8 left, 4 HL = 1/16 left. Practice 1.1: Nuclear Forces Why are massive atoms (like Uranium) more likely to be radioactive than small ones (like Carbon)? Practice 1.2: Half-Life Math A rock has a 1:7 Parent-to-Daughter ratio. If the half-life is 1,200 years, how old is it? Show steps (ratio → HL count → age): Geophysics: Convection Energy from radioactive decay in the core drives convection. Hot rock becomes less dense and rises; cool rock sinks, moving tectonic plates. Practice 1.3: Convection & Density A 45g rock sample displaces 15mL of water. Calculate its density. Based on the convection cycle, would higher or lower density cause rock to sink? Calculation (D = m/V): Explanation: Physics Final Review Part II: Waves, Light & Stars Waves & EM Radiation EM Spectrum: The full range of light waves, from radio (low energy) to gamma rays (high energy). Photon: A packet of light energy; massless but has momentum. Ionizing Radiation: Radiation with enough energy to knock electrons off atoms (harmful to cells). Doppler Effect: The change in wave frequency as a source moves toward (higher) or away (lower) from you. Gravity & Motion Universal Gravitation: Every particle with mass attracts every other particle with mass. Inverse Square Law: Gravity weakens with the square of distance (1/d2). Double distance = 1/4th force. Stellar Lifecycles Fusion: Process that powers stars by smashing hydrogen into helium. Supernova: A massive star explosion; creates heavy elements (like gold or iron) through extreme heat/pressure. Red Dwarf: Small, cool, long-lived stars. White Dwarf: The dense, hot core left over after a smaller star (like our Sun) dies. Black Hole: An area of gravity so strong that even light cannot escape; formed after massive star supernovas. Practice 2.1: Gravity Logic If the distance between Earth and the Moon tripled (3x), what would happen to the gravitational pull? Explain using the Inverse Square Law. Practice 2.2: Light & Radiation Define a photon. Why is ionizing radiation considered dangerous compared to radio waves? Practice 2.3: The Life and Death of Stars How does a star produce its energy, and what is the specific process that creates the heavy elements found on Earth? Physics Final Review Part III: Momentum & Collisions Conservation of Momentum The Law of Conservation of Momentum states that the total momentum of a system is the same before and after a collision. Momentum is only transferred between objects, never lost: Pbefore = Pafter. Practice 3.1: Momentum Check Calculate the momentum (p = m × v) of a 0.5 kg basketball thrown at 12 m/s. Show your work and units. Practice 3.2: Impulse & Safety Using F × t = Δp, explain how an airbag saves a driver's life during a crash. Focus on the Force and Time relationship: Practice 3.3: Collisions A 2,000 kg car at 10 m/s hits a stationary 2,000 kg car. They stick together. Calculate the final velocity. Is this elastic or inelastic? Apply Pbefore = Pafter logic: Human Factors Distraction increases reaction time. If a car is moving at 30 m/s, a 1-second delay is 30 extra meters of distance traveled before braking starts.
Physics Final Answer KeyTeacher Answer Key Part I: Nucleus & Earth Practice 1.1: Nuclear Forces Answer: In large nuclei, the protons are spread further apart. The Strong Force is very short-range and cannot reach across the large nucleus to hold it together, while the Electrical Repulsion is long-range and pushes the protons away, leading to radioactive decay. Practice 1.2: Half-Life Math Ratio 1:7 = 1 part Parent, 7 parts Daughter = 8 Total Parts (Fraction = 1/8). HL Count: 1 → 1/2 → 1/4 → 1/8 (3 Half-Lives) Age: 3 HL × 1,200 years = 3,600 Years Practice 1.3: Convection & Density Density: D = mass / volume = 45g / 15mL = 3 g/mL Note: Rock sinks because Higher Density (cooled rock) causes it to sink back toward the core in the convection cycle. Hotter rock has lower density and rises. Teacher Answer Key Part II: Waves & Universe Practice 2.1: Gravity Logic Answer: If distance triples (3x), the gravity becomes 1/9th of its original strength. This follows the Inverse Square Law, where force decreases as the square of the distance increases (32 = 9). Practice 2.2: Light & Radiation Answer: A photon is a massless packet of light energy that still carries momentum. Ionizing radiation (UV, X-Rays, Gamma) is dangerous because it has enough energy to strip electrons from atoms, which can damage cell DNA, unlike low-energy radio waves. Practice 2.3: Life & Death of Stars Energy Production: Stars use nuclear fusion to power themselves, smashing hydrogen atoms together into helium. Heavy Element Creation: When massive stars explode in a Supernova, the extreme heat and pressure create heavy elements (like iron and gold) that cannot be made in regular stars. Teacher Answer Key Part III: Momentum & Collisions Practice 3.1: Momentum Check p = m × v = 0.5 kg × 12 m/s = 6 kg·m/s Practice 3.2: Impulse & Safety Answer: Airbags increase the time (t) of the collision. According to the impulse formula (F × t = Δp), if the time increases for the same change in momentum, the felt by the person decreases significantly.
Physics Finale SlidesSection 9-A // Physics Physics Finale Master Practice & Review Session Practice 1.1 Why are massive atoms (like Uranium) more likely to be radioactive than small ones (like Carbon)? Think about the range of the Strong Force vs. Electric Repulsion... The Nucleus Answer In large nuclei, protons are spread further apart. The Strong Force is short-range and cannot reach across the nucleus. The long-range Electric Repulsion wins, pushing protons away! "Radiative decay happens when the glue (Strong Force) is too short to reach the edges." Practice 1.2 A rock sample has a 1:7 Parent-to-Daughter ratio. If the half-life is 1,200 years, how old is the rock? The Solution Total Parts 1+7=8 Fraction 1/8 HL Count 3 1 → 1/2 (1 HL) 1/2 → 1/4 (2 HL) 1/4 → 1/8 (3 HL) 3 × 1,200 = 3,600y Practice 1.3 A 45g rock sample displaces 15mL of water. Calculate its density. Based on the convection cycle, would higher or lower density cause rock to sink? Earth's Engine Logic D = m / V 3 g/mL Convection Result: Cooler rock becomes HIGHER density and sinks toward the core. Hotter rock becomes LOWER density and rises. EM Radiation Basics Photon A "packet" of light energy. Massless, but it still has momentum! Ionizing Radiation High-energy waves (UV, X-Ray, Gamma) that can knock electrons off atoms. The EM Spectrum The full range of light waves, from low-energy radio waves to high-energy gamma rays. Practice 2.1 Why is ionizing radiation considered more dangerous to humans than radio waves? The Energy Risk Ionizing radiation carries enough energy to strip electrons from atoms. This can damage DNA in living cells, leading to mutations or cancer. Radio waves are "non-ionizing" and lack the energy to cause this microscopic damage.
