Michael faraday was one of the first scientists to experiment with motors. how did faraday design his first motor? a.) he brought a current-carrying coil of wire close to running water. b.) he rotated a magnet around a current-carrying wire dipped in boiling water. c.) he used energy from the sun to rotate a magnet. d.) he brought a magnet close to a current-carrying wire.

Dinate system, and a charge q = - 2.00 nc is placed s2 10 n> c. (a) what is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to es from parallel to perpendicular? (b) at what absolute temperature t is the average translational kinetic energy 32 kt of a molecule equal to the change in potential energy calculated in part(: abovethistemperature, thermalagitationprevents the dipoles from aligning with the electric field.) placed in a uniform electric field e with magnitude 1.6 * 6 on the positive x-axis at x = 4.00 cm. (a) if a third charge q3 = +6.00 nc is now placed at the point x = 4.00 cm, y = 3.00 cm, find the x- and y-components of the total force exerted on this charge by the other two. (b) find the magnitude and direction of figure p21.62 ll uu 21.55 . torque on a dipole. an electric dipole with dipole moment ps is in a uniform external electric field es. (a) find the orientations of the dipole for which the torque on the dipole is zero. (b) which of the orientations in part (a) is stable, and which is unstable? (hint: consider a small rotation away from the equi- librium position and see what happens.) (c) show that for the stable orientation in part (b), the dipole’s own electric field tends to oppose the external field. 21.62 ..

1. a student believes that colder water makes fish swim faster. he sets up an experiment using different temperatures of water and measures the speed of the fish. (chapter 1 – page 9) a. what is the independent variable? b. what is the dependent variable? c. list two constants the student should have for this experiment. 2. convert 0.375 mg to grams. show your work with units in order to receive credit. (chapter 1 – page 16) 3. a race car drives one lap around a race track that is 500 meters in length. (chapter 2 – pages 45-46) a. what is the driver’s displacement at the end of the lap? b. how is his displacement different from the distance traveled? 4. how far does a car travel in 90 seconds if it is traveling at a speed of 55 m/s? show the appropriate equation from your textbook and show your work with units in order to receive credit. (chapter 2 – pages 46-47) 5. two cars, both with a mass of 500 kg, are traveling down a road. the first car has a velocity of 65 m/s east and the second car has a velocity of 85 m/s west. (chapter 2 – pages 54-55) a. calculate the momentum of both cars showing the appropriate equation from your textbook and your work with units in order to receive credit. b. which car has the larger momentum? explain how you know. 6. an airplane traveling at 60 m/s comes to a stop in 10 seconds. calculate the airplane’s acceleration. show the appropriate formula and show your work with units in order to receive credit. (chapter 2 – pages 57-58) 7. an individual has a weight of 735 newtons. what is the individual’s mass? show the appropriate equation from your book and show your work with the units in order to receive credit. (chapter 3 – pages 78-79) 8. in terms of newton’s first law of motion, explain why it is important to wear a seatbelt while riding in a car. (chapter 3 – page 86) 9. if you kick a tennis ball with 50 n of force and then kick a soccer ball with 50 n of force, explain the difference in their motion according to newton’s second law. (chapter 3 – pages 81-82) 10. describe how the velocity and acceleration of a skydiver changes as she falls from the plane back to the ground. (chapter 3 – pages 88-89) 11. a child is swinging on swing. describe what happens to both the kinetic energy and potential energy of the child as she swings up and down. (chapter 4 – pages 123) 12. driving to work one morning, you get a flat tire. when using the car jack, you apply 120 n of force to the jack and the jack in turn applies 2000 n of force to lift the car up. what is the mechanical advantage of the jack? (chapter 4 – page 111) 13. a temperature of a 50 kg block increases by 15°c when 337,500 j of thermal energy are added to the block. (chapter 5 – pages 141-142) a. what is the specific heat of the object? show the appropriate equation from your book and show your work with units. b. what is the block made of? use the chart on page 141. c. is this block a good material for insulators or conductors? 14. explain why gases make better thermal insulators than solids or liquids. give one example from the textbook of a thermal insulator that can keep you warm on a cold day. (chapter 5 – pages 147) 15. several days after a snowfall, the roofs of some homes on your street have almost no snow on them, while the roofs on other homes are still snow covered. assuming they have all received the same amount of sunlight, give one reason for this observation related to thermal energy and insulation. 16. if you purchased a string of lights, how could you determine if the lights were wired in series or parallel? (chapter 6 – pages 185-186) 17. what happens to the current in a device if the resistance is decreased but the voltage stays the same? (chapter 6 – pages 181-182) 18. you measure the voltage difference of a circuit to be 15 v and the resistance to be 675 ω. what is the current in the circuit? show the appropriate equation from your book and show your work with units. (chapter 6 – page 182) 19. explain why a magnet from your refrigerator could not be used to lift something as heavy as a car. (chapter 7 – pages 202-203)

J. j. thomson’s experiment disproved the theory that an atom