Regents Physics in Four Pages Unit Conversion Sample Problem: 1. Convert 12 ev into Joules 2. Convert 7 elementary charges into Coulombs 3. How many universal mass units are in 1200 MeV Graphical Relationships Strategy: Set up the variables so they are in a y = f(x) format and identify relationship Ignore all variables except y and x Sample Problem: 4. Which graph best represents the relationship between the absolute index of refraction (X) of these substances and the corresponding speed of light (Y) in these substances? 5. Which graph best represents the relationship between kinetic energy (Y) and velocity (X) for a moving object? 6. Which graph best represents the relationship between height (X) and gravitational potential energy (Y) for an object? 7. Which graph best represents the relationship between force of gravity (Y) and the distance (X) between a satellite and the Earth? Conceptual Questions: 8. A ball is dropped from the top of a cliff. Which graph best represents the relationship between the ball s total energy (Y) and elapsed time (X) as the ball falls to the ground? [Neglect friction.] 9. Which graph best represents the relationship between the acceleration (Y) of an object falling freely near the surface of Earth and the time (X) that it falls? Kinematics Strategy: List givens and what the question is asking for, find equation on reference table **Note: This strategy works on many physics problems** Sample Problem: 10. A train accelerates from 12 to 20 meters per second over a distance of 200 meters. Calculate the acceleration of the train. 11. On planet X, a bar of soap falls from a height of 2 meters in 3.5 seconds. What is acceleration due to gravity on planet X? Conceptual question 12. A dart gun shoots a dart directly upwards. What is the dart s speed and acceleration at the peak of its journey?
Graphing Motion Strategy: Think about what an object is doing rather than trying to memorize matching graphs. For example an object with constant velocity will have a constant velocity graph, the displacement graph will go up (or down) at a constant rate, and the acceleration will be zero. 13. Which graph would best represent a. speed vs. time for an unmoving object b. displacement vs. time for an object moving with a constant speed c. speed vs. time for a decelerating object d. distance vs. time for an object with increasing speed e. acceleration vs. time for an object that is moving at a constant speed f. displacement vs. time for an object that is moving toward its point of origin g. acceleration vs. time for an object that is increasing its speed at a constant rate h. displacement vs time for an object thrown upward i. velocity vs time for an object thrown upward Strategy: DVA Sample Problem: 14. What is the acceleration from 4-5s? 15. What is the acceleration from 7-8 seconds? 16. How fast is the object going at t=3 seconds? 17. What is the total displacement from 0-4 seconds? 2D Motion (Vectors) Vocabulary: Scalar, vector, distance, displacement, speed, velocity, acceleration, magnitude, resultant Strategy: Tip-to-tail - To determine the resultant from two vectors, we move the beginning (tail) of one vector to the end (tip) of the other vector. The resultant then points from start to finish 18. 19. An ice skater skates 12 meters north and 5 meters west, in 22 seconds a. Calculate her distance b. Calculate her displacement c. Calculate her speed d. Calculate her velocity Strategy: Riverboat Problem: Always draw a picture for 2D problems. Or two (distance and speed) 20. A boat is traveling West at 12 m/s across a river which is flowing North at 5 m/s. a. What is the magnitude of its its resultant velocity? b. How much time will it take the boat to cross the 200 m wide river?
Sample Problem: Min/Max Resultant: 21. A 12 N force and 7 N force act on an object. a. What should the angle be between the two to get a maximum resultant? How much is the resultant? b. Angle for minimum? How much is the resultant? 2D Motion (Projectile Motion) Strategy: Use the x/y table. List your givens. Make sure not to mix X and Y variables. Givens: a x = 0, a y = -9.8 m/s 2 for all projectile motion problems Horizontally launched: vi y = 0 (in other words, v i is entirely horizontal) Launched at an angle: vf y = 0 at the peak, use A x = Acos(θ), A y = Asin(θ) to get vi x and vi y Sample problem: 22. A plane traveling horizontally at 150 m/s drops a package from a height of 6000 m. How much time does it take the packages to reach the ground? 23. A soccer ball is kicked with an initial speed of 22 m/s at an angle of 35 degrees from the horizontal. a. What is the initial horizontal velocity of the soccer ball? b. What is the initial vertical velocity of the soccer ball? c. How much time will it take the soccer ball to reach its maximum height? d. How much total time will the soccer ball spend in the air? Conceptual Questions: 24. A large cannon shoots a 100 kg shell at a target. a. What angle (from the horizontal) will produce the maximum range? b. What angle will leave the projectile in the air for the most time? c. What shape will the path of the projectile take for any angle? 25. A 2 kg rock is fired horizontally off a cliff at 20 m/s, and a 4 kg rock is fired at 10 m/s from the same cliff. If it takes 3 seconds for the 2 kg rock to hit the ground, how much time does it take for the 4 kg?7. Two ways to calculate F net : Forces What does F g mean? How do you calculate F g? What does F N mean? F N usually is equal to F g because Ff Fs
What does equilibrium mean? Describe the motion of an object in equilibrium 26. What has more inertia an elephant at rest, or a mouse moving at 4 m/s? 27. A 20 N force pulls a 10 kg object North along a rough surface. The object accelerates at 1.5 m/s 2. a. What is the net force on the object? b. What is the force of friction on the object? c. In what direction does friction point? 28. A rocket provides 10,000 N of thrust to move with constant velocity. What is the net force on the rocket? 29. A rocket provides 10,000 N of thrust to move with constant velocity. What is the weight of the rocket? 30. A 2 x 10 3 kg elephant is blocking the hallway to go to physics class. The elephant says it will lonely move if you calculate the normal force acting on it. Calculate the normal force acting on the elephant so it ll move. 31. What is the force of gravity acting on a 75 kg student? What is another word for this force? 32. A 1 kg hammer pushes on a 0.01 kg nail with a force of 100 N. With what force does the nail push on the hammer? 33. How much force is necessary to move a 12 N copper box on steel with constant speed? 34. An 850 N skier on waxed skis on snow is traveling at 10 m/s. How much force must he provide to keep moving at that speed? 35. A 200 N force pulls a 40 kg object across a steel surface at constant speed. Calculate the coefficient of kinetic friction between the object and the surface as it moves? Two ways to calculate impulse: Impulse/Momentum Sample problem: 36. Calculate the impulse for each case acting on a 1.5 kg object a. Accelerating from rest to 2 m/s b. 2N force acts for 3 s c. 4 N force acts for 1.25 s d. Accelerating from 2 m/s to 5 m/s 37. A car traveling at 20 m/s has a momentum of 23,000 kg m/s. What is its mass? 38. A 200 kg cannon shoots a 10 kg cannonball to a speed of 60 m/s. What impulse does the cannon exert on the ball? 39. A baseball bat hits a baseball with a force of 300 N for 0.1 seconds. What is the change in momentum of the baseball? Strategy: Conservation of Momentum (collisions/explosions): Read the question carefully and ensure that your equation matches the description of the problem. Sample Problem 40. A 60 kg boy running at 6 m/s jumps into a 40 kg boat at rest. After he lands in the boat, how fast are he and the boat (together) moving?
Circular Motion Circular Motion & Universal Gravitation Universal Gravitation 40. What is the centripetal acceleration of a toy ball on the end of a 1.44 meter long string if it is moving at 12 meters per second? 41. Calculate the speed experienced by a rider on a carnival Graviton ride if the ride provides an acceleration of 14 m/s 2 at a distance of 4 meters from the center? 42. Determine the gravitational force of attraction experienced by two 5.0 kilogram masses separated by a distance of 2.5 meters. 43. Determine the force of gravity between the Earth and a 1200kg satellite orbiting with a distance of 2x10 7 m from the center of the Earth. Strategy: Ratios: To find out what happens to Fg (or any quantity) when something changes, simply put a 1 into the equation for everything that stays the same, 2 for double, 3 for triples, 0.5 for half, etc. Sample Problem: 44. What happens to centripetal acceleration when speed is halved? 45. What happens to the force of gravity between two objects if the distance between both objects doubles? Work, Power, & Energy Strategy: Same as always, list givens then choose equation. Remember, work can be calculated 2 ways. Work = Power = KE = PE = PEs = 46. An 6,000 N elevator goes from up 20 meters in 5 seconds. Calculate the power generated by the elevator. 47. How much work does it take to accelerate a 5 kg object from rest to 7 m/s? 48. 12 J of potential energy are stored in a spring which is compressed 0.12 m. Determine the spring constant of the spring
Conservation of Energy- Energy is never lost or gained, only converted from one form to another. When energy is lost to heat or friction, we call that internal energy or work done against friction. 49. A 3 kg rock is thrown upwards with 12 J of kinetic energy. What maximum height will it reach? 50. A marble launcher spring is stretched until it has 90 J of elastic potential energy. How much kinetic energy will the marble have when it is launched? 51. A 1200 kg car is atop a 12 meter tall hill. It reaches the bottom with 120,000 J of kinetic energy. How much work was done against friction as it rolled down the hill? Conceptual Questions: 52. A car travels up a hill at constant speed. What happens to its kinetic and potential energy? 53. A car uses its brakes to stop on a level road. During this process, there must be a conversion of kinetic energy into 1. light energy 2. nuclear energy 3. gravitational potential energy 4. internal energy 54. As a pendulum swings from its high point to its low point, what happens to A. Kinetic energy? B. Potential energy? C. Total energy? Charge is quantized Electrostatics 55. Calculate the charge in Coulombs for an object with 7 excess electrons 56. Calculate the charge in Coulombs for an magnesium ion with 12 protons and 10 electrons. 57. How many excess electrons are on an object with a net charge of 6.4 x 10-18 C? 57. Could the following quantities of charge be found on an object: a. 4.7 e b. 7 e c. 2.4 x 10-19 C d. 2.4 x 10-18 C e. 4.8 x 10-19 C Charge is conserved never created or destroyed, only transferred When charge transfers, only electrons move. 58. A conducting sphere (A) with a net charge of 2.5 nc is brought into contact with an identical conducting sphere (B) with a charge of -4.5 nc. a. Calculate the net charge on the first sphere (A) after contact (in C). b. Calculate the number of excess electrons on the first sphere (A) after contact. c. Did the second sphere (B) gain electrons, lose electrons, gain protons, lose protons Electrostatics Equations Hint: There is only one equation on the reference table with Electric Field Strength 59. Calculate the electrostatic force between two electrons separated by 5 nm. 60. Calculate the electrostatic force on an electron in an electric field of strength 12 N/C. 61. Two charged spheres separated by 1 meter have an electrostatic force of 2 N between them. What will the force be if the distance between them is decreased to 0.5 m? 62. A charged object experiences an electrostatic force of 12 N when in an electric field of 20N/C. What is the charge of the object? 63. Calculate the electrostatic force between two charged objects each with charge 20 nc when separated by 60 micrometers.
Circuits Circuit Equations: V = W/q I = q/t R = ρl/a R = V/I P = VI = I 2 R = V 2 /R W = Pt Strategy: Same as always, list your givens before choosing an equation. 64. What is the current through a wire if 240 coulombs of charge pass through the wire in 2.0 minutes? 65. A 10-meter length of wire with a cross-sectional area of 3.0 10-6 square meter has a resistance of 9.4 10-2 ohm at 20 Celsius. What material is the wire made of? 66. Calculate the resistance of 1.00-kilometer length of nichrome wire with a cross-sectional area of 3.50 10-6 meter 2 at 20 C. 67. What is the total amount of work required to move a proton through a potential difference of 100 volts? 68. A potential drop of 50 volts is measured across a 250-ohm resistor. What is the power developed in the resistor? 69. In a simple electric circuit, a 24-ohm resistor is connected across a 6-volt battery. What is the current in the circuit? Conceptual Problems Strategy: Think of a resistor as a traffic jam, with current being the motion of traffic and voltage being a pressure pushing the cars through. Making a resistor longer or adding more resistors in series makes the traffic worse (resistance goes up, current goes down), and making it wider or adding more in parallel makes the traffic better (resistance goes down, current goes up) 70. One resistor is set up in a circuit. When another is added in series, what happens to current and resistance? 71. One resistor is set up in a circuit. When another is added in parallel, what happens to current and resistance? Circuit Analysis Strategy: Use a VIRP chart! Sample problem 72. A 4 ohm and 5 ohm resistor are set up in series and connected to an 18V battery. A voltmeter is connected to the 5 ohm resistor. Make a sketch of the circuit and determine the reading of the voltmeter. 73. A 3, 4, and 5 ohm resistor are set up in parallel and connected to a 1.5 V battery. Determine the total current running through the circuit. 74. Two 4-ohm resistors are set up in parallel and connected to a 12 V battery. Determine the power consumed by the circuit. Note: Circuit diagrams were not included in this to save space. Please go over problems with circuit diagrams as circuits are a large portion of the Regents exam. Magnetism & Fields Magnetism is due to the motion of Moving charged particles create a Changing magnetic field creates a Rules for fields: Field lines never cross, Field lines closer together = higher strength Magnetic fields Electric fields
Waves Concepts/Vocabulary: Period, Frequency, Transverse, Longitudinal, Amplitude, Wavelength, Resonance, Diffraction, Interference, Doppler effect, Node & Anti-node Strategy: Waves are very conceptual. It is important that you know and understand the concepts for waves. Also there will be at least one multi-part question on the Regents with n1sin 75. What is the period of a water wave if 4 complete waves pass a fixed point in 10 seconds? 76. If the frequency of a wave is doubled, what happens to its period? 77. What is the frequency of a wave with wavelength 0.5 meters and period 2.0 seconds? 78. A 512 Hz sound wave travels 100 meters through air at STP. What is its wavelength? 79. Are sound waves transverse or longitudinal? Are light waves transverse or longitudinal? 80. An earthquake wave is traveling from west to east through rock. If the particles of the rock are vibrating in a north-south direction, the wave must be classified as: transverse or longitudinal? 81. A periodic wave has frequency 12 Hz, amplitude of 0.25 meter, and wavelength of 3.0 meters. What is its speed? 82. A periodic wave has a period of 0.25 seconds and wavelength of 2.0 m. What is its speed? 83. A pulse in a slinky has an amplitude of +20 cm. What must the amplitude be of a pulse to completely destructively interfere with the original pulse? 84. A train whistle has a frequency of 720 Hz. As the train is moving away from you, will the frequency you hear be higher, lower, or the same? 85. Which travels faster in a vacuum, gamma rays or radio waves? 86. What type of electromagnetic wave has a frequency of 2x10 9 Hz. EM Wave Equations 87. How fast does a light wave with frequency 5.09 x 10 14 Hz travel in crown glass? Note: There are ALWAYS problems calculating angle of refraction worth multiple points on the Regents Note: ALWAYS MEASURE ANGLE OF REFLECTION/REFRACTION FROM THE NORMAL 88. A light wave in air is incident on corn oil with an angle of 25 degrees from the normal. Calculate the angle of refraction in corn oil. And what is the angle of reflection? Modern Physics Energy Levels Electrons can move between energy levels in an atom, but can t exist between levels. You can calculate the energy in ev by subtracting the energy at each level. Sample problem 89. An excited electron in the d-level of a mercury atom emits a photon and returns to ground state. What is the energy in ev? In J? Ephoton You can relate the energy/frequency of a photon. Always use energy in J 90. What is the frequency of the problem from 89? What classification of photon is it? Mass/Energy are equivalent, and there are two ways to convert between them 91. If a deuterium nucleus has a mass of 1.53 10-3 universal mass units less than its components, determine the energy this represents in MeV 92. Determine the energy lost when 1.5 x 10-19 kg are converted into energy Subatomic particles Use the table on the reference table to determine the charge of particles based on their quark content. 93. Determine the charge of an anti-charm quark in Coulombs 94. A particle is made of an up and anti-bottom quark. What classification of matter is this, and what is its charge in elementary charges? 95. Is a neutron uud or udd? How can you be sure?