AP Physics 2 Questions on Mass-Energy Equivalence and Nuclear Applications

📚 Quick Study Guide

• ⚛️ Mass-Energy Equivalence: Einstein's famous equation $E=mc^2$ relates energy ($E$) and mass ($m$), where $c$ is the speed of light (approximately $3 \times 10^8$ m/s). This equation shows that mass can be converted into energy and vice versa.
• ☢️ Mass Defect: The mass defect is the difference between the mass of a nucleus and the sum of the masses of its constituent nucleons (protons and neutrons). This mass difference is converted into the binding energy that holds the nucleus together.
• 🤝 Binding Energy: The energy required to separate a nucleus into its individual protons and neutrons. It is equivalent to the mass defect according to $E=mc^2$. Higher binding energy per nucleon indicates a more stable nucleus.
• ⚡ Nuclear Reactions: Reactions involving the nuclei of atoms, such as nuclear fission (splitting of a heavy nucleus) and nuclear fusion (combining of light nuclei). These reactions release or absorb tremendous amounts of energy.
• 📅 Half-Life: The time required for half of the radioactive nuclei in a sample to decay. It is a characteristic property of each radioactive isotope.

🧪 Practice Quiz

1. What does $E=mc^2$ represent?
   1. (A) Energy equals mass times the speed of sound squared.
   2. (B) Energy equals mass times the speed of light squared.
   3. (C) Energy equals mass divided by the speed of light squared.
   4. (D) Energy equals mass plus the speed of light squared.
2. What is mass defect?
   1. (A) The increase in mass during nuclear fission.
   2. (B) The decrease in mass during nuclear fusion.
   3. (C) The difference between the mass of a nucleus and the sum of the masses of its constituent nucleons.
   4. (D) The mass of electrons in an atom.
3. What is binding energy?
   1. (A) The energy that binds electrons to the nucleus.
   2. (B) The energy required to separate a nucleus into its individual protons and neutrons.
   3. (C) The energy released during a chemical reaction.
   4. (D) The energy of photons emitted by an atom.
4. Which process involves the splitting of a heavy nucleus?
   1. (A) Nuclear fusion
   2. (B) Nuclear fission
   3. (C) Alpha decay
   4. (D) Beta decay
5. Which process involves the combining of light nuclei?
   1. (A) Nuclear fission
   2. (B) Nuclear fusion
   3. (C) Gamma radiation
   4. (D) Chain reaction
6. What is half-life?
   1. (A) The time it takes for all radioactive nuclei to decay.
   2. (B) The time it takes for half of the radioactive nuclei to decay.
   3. (C) The average lifetime of a radioactive nucleus.
   4. (D) The time it takes for a nucleus to double in size.
7. If a radioactive substance has a half-life of 10 years, how much of the substance will remain after 20 years?
   1. (A) None
   2. (B) One-quarter
   3. (C) One-half
   4. (D) All of it