m, kg, s, ampere, mole, K

Transcription

1 Q1. What is the diameter of a proton? m Q2. What is the extent of the visible universe? m Q3. What is the mass of an electron? kg Q4. What is the mass of the universe? kg Q5. How long does light take to pass a nucleus? Q6. What is the age of the universe? s s 100 Concepts with Tips Q7. State the 6 fundamental units in the SI system. m, kg, s, ampere, mole, K Q8. The effect of which type of error is reduced by repeated measurement? Random Q9. What is the difference between accuracy and precision? accuracy (how close a measurement is to the accepted value precision (the agreement among a number of measurements made in the same way)? Q10. What is the difference between instantaneous and average velocity? Slope of tangent versus slope of chord of displacement time graph Q11. What is the difference between linear and proportional graphs? proportional (passes through the origin) Q11. What two conditions are necessary before you can apply the kinematic equations? Straight line motion and constant acceleration Q12. What forces act on an object travelling at terminal velocity? Weight and fluid resistance Q13. What does the area under a velocity-time graph represent? Displacement Q14. What does the slope of a velocity-time graph represent? Acceleration Q15. State Newton s First Law of Motion. Every object travels in a straight line at constant speed or remains at rest, unless acted upon by a net external force. Q16. State the condition for translational equilibrium. No net force Q17. State Newton s Second Law of Motion.

2 Net force equals rate of change of momentum Q18. State the Law of Conservation of Linear Momentum. In a closed system, momentum is conserved in all collisions. Q19. State Newton s Third Law of Motion. "For every action there is an equal and opposite reaction." IB wants "When a force acts on a body an equal and opposite force acts on the other body" Q20. What does the area under a force-displacement graph represent? Work done Q21. State the law of conservation of energy. Energy cannot be created or destroyed, it merely changes form. Q22. What is the difference between an elastic and an inelastic collision? Energy is conserved in an elastic collision. Q23. Define power. Rate of using energy or rate of doing work Q24. Define efficiency. Work out compared to energy in Q25. What can be said about the acceleration of an object describing uniform circular motion? Constant, towards centre of circle Q26. What determines the direction of thermal energy transfer between objects? Their temperatures Q27. What is the relationship between the Kelvin and Celsius scales of temperature? C = K Q28. What is the internal energy of a substance? Total potential energy and random kinetic energies Q29. List three thermal macroscopic concepts. Temperature, internal energy, thermal energy (heat) " heat is a non-mechanical transfer of energy" Q30. Define heat capacity of an object. Energy required to raise temperature by one K Q31. Define specific heat capacity. Energy required, per kilogram, to raise temperature by one K Q32. What is the change of phase from gas to liquid called? Condensation Q33. Distinguish between evaporation and boiling. Evaporation occurs below boiling point, and only at the surface. Boiling occurs at a constant temperature. Q34. Define specific latent heat. Energy per unit mass absorbed or released during a phase change Q35. Define pressure.

3 Force per unit ar proportional (passes through the origin) ea acting on a surface Q36. State the defining equation of SHM Q37. State what is meant by damping. When a force is always in the opposite direction to the direction of motion of the oscillating particle (NOTE: this force is a dissipative force) Q38. State what is meant by resonance. a transfer of energy in which an oscillating force matches system resulting in a large amplitude of vibration Q39. Define wave speed. speed of transfer of the energy of the wave the natural frequency of the Q40. List the seven principal electro-magnetic radiations from lowest to highest energy. Radio waves, microwaves, infra-red, visible, UV, X-ray, gamma rays f: Hz Q41. State Snell s Law. For any two media the ratio of sin i to sin r is a constant Q41A. State the principle of superposition. When pulses and waves (unlike particles) cross the net displacement of the medium (through which waves travel) is equal to the vector sum of the individual displacements. Q41B. Coherent light sources have a constant phase difference, and the same wavelength. Q42. What is a force field? "a region in space where an object will experience a force due its charge or mass." Q42. Define electric potential difference. Work per unit charge needed to move a charge from one point to another. Q43. Define the electronvolt. The energy an object with the charge of one electron acquires after being accelerated through a PD of one volt. Q44. Define Ohm s Law. The current flowing through a device is proportional to the potential difference applied across it providing the temperature is constant. (NOTE: R = V/I is not Ohm s Law) Q45. What is the resistance of an ideal voltmeter? Infinite Q46. Define gravitational field strength? Gravitational force per unit mass on a point mass Q47. State the Law of Conservation of Charge. The total electric charge of an isolated system remains constant Q48. State Coulomb s Law. The electric force between two point charges is directly proportional to the product of the two charges and inversely proportional to square of the distance between them, and directed along the line joining the two charges.

4 Q49. What is meant by a radial field? Straight lines emanating from a point. Q50. What causes magnetic fields? Moving charges Q51. Describe a simple model of the atom. Electrons orbit a nucleus as a result of electrostatic attraction. Q52. What evidence supports the nuclear model of the atom? Geiger-Marsden expt Q53. Outline one limitation of the simple model of the nuclear atom. Accelerating charges radiate energy atoms collapse! (and what holds the protons together?) Q54. Define nuclide. A member of an atomic species Q55. Define isotopes. Atoms with same atomic number, but different mass numbers. Q56. Define nucleon. Protons and neutrons Q57. Describe what is meant by radioactive decay. (i)unstable nuclei randomly change/emit energy (ii) by the release of alpha particles, electrons, gamma rays Q58. Describe the ionizing properties of alpha, beta and gamma radiation. Alpha is the most ionizing (but short range) Q59. Outline the biological effects of ionizing radiation. Cells can die, or mutate (if DNA is changed) Q60. How does the rate of decay of a radioactive sample change over time? Decreases exponentially Q61. Define radioactive half-life. The time it takes for half the nuclei in a sample to decay. Q62. Give an example of artificial transmutation. Q63. Define the term unified atomic mass unit. One twelfth the mass of an atom of Q64. Define mass defect. The difference between the mass of a nucleus, and its component nucleons. Q65. Define binding energy. The energy needed to completely separate the components of a nucleus. The energy released when a nucleus is assembled from its components. Q66. Describe nuclear fission.

5 Large nuclei are broken into smaller nuclei, and energy is released. Q67. Describe nuclear fusion. Small nuclei join together to form larger nuclei, and energy is released. Q68. What is the main source of the sun's energy? Nuclear fusion Q69. State the Second Law of Thermodynamics. (i) Thermal energy may be completely converted to work in a single process, but (ii) continuous conversion requires a cyclical process and the transfer of some energy from the system Q70. What is meant by degraded energy? In any process that involves energy transformations, the energy transferred to the surroundings is no longer available to do useful work. Q71. What is the principal mechanism in production of electrical power? Rotate coils in a magnetic field. Q72. What is the prime source of world energy? The Sun. Q73. Define energy density. Ratio of the energy released from the fuel to the mass of the fuel consumed Q74. State the relative proportions of energy use. Oil 37% Coal 27% Natural Gas 23% Nuclear 7% Hydro 7% Q75. What are the historical and geographical reasons for the widespread usage of fossil fuels? (i) Industrialisation led to high energy use (ii) so industry developed near large supplies of fossil fuels Q76. List the overall efficiencies of power stations fuelled by different fossil fuels. Natural gas 45% Oil 38% Coal 35% Q77. Which neutrons initiate chain reactions? Low energy (1 ev) Q78. Define critical mass. The minimum number of fissionable nuclei in order to sustain a chain reaction. Q78. What is fuel enrichment? Naturally occurring uranium contains less than 1% U-235. Q79. What is the role of a moderator in a thermal fission reactor? To slow down neutrons (fast moving neutrons pass through nuclei.) Q80. What is the role of the control rods in a thermal fission reactor? They absorb neutrons to control the rate of the reaction. Q81. What is the role of the heat exchanger in a thermal fission reactor? Water is piped through the core, so the nuclear reaction can be separated from the environment. Q82. What is the result of neutron capture by U-238? Pu-239

6 Q83. What is the main problem with obtaining power from nuclear fusion? Confining a high-temperature high-density plasma Q84. What energy transfer occurs in a photovoltaic cell? Solar to electrical Q85. What energy transfer occurs in a solar heating panel? Solar to thermal Q86. What are the basic features of a wind generator? 1. Tower to support rotating blades. 2. Blades that can be rotated to face into the wind. 3. Generator. 4. Storage system or connection to a distribution grid Q87. How does an OWC operate? 1. Wave capture chamber is set into rock face on land where waves hit the shore. 2. Tidal power forces water into a partially filled chamber that has air at the top. 3. This air is alternately compressed and decompressed by the oscillating water column. 4. These rushes of air drive a turbine which generates electrical energy. Q88. Define albedo. The ratio of radiation reflected compared to incident radiation. Q89. State factors which determine the albedo of a planet. Cloud formation, nature of surface (ice, water, forest etc ) Q90. Describe the greenhouse effect. IR radiation passes through the atmosphere and warms the earth. Longer wavelength IR is reradiated. This radiation is absorbed by atmosphere and reradiated. Q91. Identify the main greenhouse gases and their sources. 1. Methane (livestock, fermentation of plant matter) 2. Water 3. Carbon dioxide (burning fossil fuels, deforestation) 4. Nitrous oxide (livestock and industry) Q92. Explain the molecular mechanism by which greenhouse gases absorb IR radiation. The natural frequency of oscillation of greenhouse gases matches the frequency of the IR radiation. This causes resonance. Q93. State the Stefan-Boltzmann law. Q94. Define surface heat capacity. The energy required to raise the temperature of a unit area of a surface by one Kelvin. Q95. What is meant by the enhanced greenhouse effect? An increase in the greenhouse effect due to human activities. Q96. What evidence links global warming to the enhanced greenhouse effect?

7 Ice core data shows a link between atmospheric and temperature. Q97. Outline some mechanisms that may increase global warming. Global warming reduces ice and snow cover, which in turn reduces the albedo. This will result in an increase in the overall rate of heat absorption. Temperature increase reduces the solubility of CO 2 in the sea and increases atmospheric concentrations. Deforestation results in the release of more CO 2 into the atmosphere due to slash-and-burn clearing techniques, as well as reduces the number of trees available to provide carbon fixation. Q98. Define coefficient of volume expansion. The ratio of change in volume per degree change, compared to original volume. Q99. Why is difficult to predict a rise in sea-level? Anomolous expansion of water. (Between O and 4 degrees water contracts.) Q100. List some ways to reduce the enhanced greenhouse effect. Advances in technology (decarbonise exhausts, increase efficiency, fusion reactors) Reduce energy requirements Replace use of oil and coil with renewable energy Plant trees and protect forests