PHYS_2C_ELC_-_Finals_Study_Jam

Physics 2C ELC Finals Study Jam – 1 – 1. Rank the densities of the objects A, B, and C. a. 𝜌 ? > 𝜌 ? > 𝜌 ? b. 𝜌 ? > 𝜌 ? > 𝜌 ? c. 𝜌 ? > 𝜌 ? > 𝜌 ? d. 𝜌 ? > 𝜌 ? > 𝜌 ? e. 𝜌 ? > 𝜌 ? > 𝜌 ? 2. Consider two identical simple pendulums of length L. The first pendulum is displaced from its equilibrium position by an angle ? 𝑚 and released. The second one is displaced from its equilibrium position by an angle 2? 𝑚 and released. The pendulums then execute simple harmonic motion with periods 𝑇 1 and 𝑇 2 respectively. Which of the following is true about these time periods? a. 𝑇 2 = √2 𝑇 1 b. 𝑇 2 = 𝑇 1 /2 c. 𝑇 2 = 𝑇 1 d. 𝑇 2 = 4𝑇 1 e. 𝑇 2 = 2𝑇 1 3. A beaker is filled water up to height ℎ . There is an outlet at a height ℎ/4 from the base, which is opened at the start of the experiment. If water flows from the outlet at velocity initially, what is the velocity ? 0 at the outlet when half the contents of the beaker have flowed out? You may assume that the beaker is very large compared to the size of the outlet. a. ? 0 √3 b. ? 0 √2 c. ? 0 3 d. ? 0 2 e. ? 0 4. Two identical beakers rest on weight scales and are filled with water. Beaker B has an iron sphere submerged in it, that is also connected to the ceiling by a taut string as shown in the figure. The water level is the same in both beakers. If the scales measure weights ? ? and ? ? , which of the following is true? a. ? ? = ? ? b. ? ? > ? ? c. ? ? < ? ? d. Insufficient information to determine the relationship between ? ? and ? ? .

Physics 2C ELC Finals Study Jam – 2 – 5. A Physics 2C student is creating water waves by throwing pebbles with a frequency of 2.0 ?? into a pool of water. If she now decreases the frequency of throwing the pebbles, what will happen to the velocity and the wavelength of the resulting water waves? a. Both the wavelengths of the water waves and the velocity of the water waves will remain the same. b. The wavelength of the water waves will remain the same and the velocity of the water waves will decrease. c. The wavelength of the water waves will decrease and the velocity of the water waves will remain the same. d. The wavelength of the water waves will increase and the velocity of the water waves will remain the same. e. The wavelength of the water waves will remain the same and the velocity of the water waves will increase. 6. The device shown below is used to measure the flow rate of a liquid of density 𝜌 = 7.00 × 10 2 ?𝑔 ? 3 ⁄ , through a hose having an outlet radius of ? 2 = 1.20 ?? . If the pressure difference is measured to be 𝑃 1 − 𝑃 2 = 1.20 ?𝑃𝑎 and the inlet tube to the meter has a radius ? 1 = 2.40 ?? , find the speed of liquid as it leaves the hose. Express your answer in ?/? up to 2 decimal places. 7. A mass on a spring is undergoing simple harmonic motion with a frequency of 0.20 ?? . At time ? = 0 , it is at the equilibrium point. At which one of the following times is it furthest in distance from the equilibrium point? a. ? = 2.5 ? b. ? = 3.5 ? c. ? = 5.0 ? d. ? = 7.0 ? e. ? = 7.5 ? 8. A balloon filled with helium (whose envelope has negligible mass) is tied to a uniform string of length ? = 2.0 ? and mass ? = 0.05 ?𝑔 . The balloon is spherical with a radius ? = 0.2 ? . When released in air, the balloon lifts a length ℎ of the string and remains stationary as shown in the figure. Given that 𝑝 𝑎𝑖𝑟 = 1.20 ?𝑔/? 3 and 𝜌 𝐻𝑒 = 0.179 ?𝑔/? 3 , determine ℎ in meters up to 2 decimal places. You may use 𝑔 = 9.8 ?/? 2 .

Physics 2C ELC Finals Study Jam – 4 – 14. A source emits sound with a frequency of 1000 ?? . Both it and an observer are moving in the same direction with the same speed, 100 ?/? . If the speed of sound is 340 ?/? , the observer hears sound with a frequency of: a. 290 ?? b. 540 ?? c. 1000 ?? d. 1800 ?? e. 3400 ?? 15. A piano tuner using a 264 ?? tuning fork hears 2 beats per second while playing the tuning fork and a piano key at the same time. What are the two possible frequencies of vibration of the piano wire? a. 260 ?? and 262 ?? b. 262 ?? and 266 ?? c. 262 ?? and 268 ?? d. 264 ?? and 268 ?? e. 266 ?? and 268 ?? 16. A tuning fork is sounded above a resonating tube (one end closed), which resonates at a length of 0.2 ? and again upon extension at 0.6 ? . If the tube length were extended even further, at which point will the sound from the tuning fork again resonate in the tube? a. 0.8 ? b. 1.0 ? c. 1.2 ? d. 1.6 ? e. 2.0 ? 17. On a windy day, a 1200 ?? warning siren on the town hall sounds. The wind is blowing at 55 ?/? in a direction from the siren toward a person standing 1 ?? away. With what frequency does the sound wave reach the person? (The speed of sound in air is 330 ?/? .) a. 1000 ?? b. 1030 ?? c. 1200 ?? d. 1400 ?? e. 1440 ?? 18. At 20°? , a pipe open at both ends resonates at a frequency of 440 ?? . At what frequency does the same pipe resonate on a particularly cold day when the speed of sound is 3% lower than it would be at 20°? ? a. 414 ?? b. 427 ?? c. 433 ?? d. 440 ?? e. 453 ??

Physics 2C ELC Finals Study Jam – 5 – 19. A bat flying at 5.0 ?/? emits a chirp at 40 ??? . If this sound pulse is reflected by a stationary wall, what is the frequency of the echo received by the bat? Assume that the speed of sound in air is 345 ?/? and express your answer in kHz up to 2 decimal places. 20. A standing wave is set up in a 2.0 ? string fixed at both ends. The string vibrates in 5 distinct segments when driven by a 120 ?? source. In how many of the segments will the string vibrate if the tension is increased by a factor of 4? a. 3 b. 10 c. 20 d. 30 e. No standing wave pattern will be observed. 21. If the electric field in a plane electromagnetic wave is given by ? ⃑ = ? ̂? 𝑚 sin (?? + 𝜔?) , then the magnetic field in this wave is: a. ? ⃑ = −?̂ 𝐸 𝑚 𝑐 sin(?? + 𝜔?) b. ? ⃑ = ?̂ 𝐸 𝑚 𝑐 sin(?? + 𝜔?) c. ? ⃑ = ?̂? 𝑚 sin(?? + 𝜔?) d. ? ⃑ = −?̂ 𝐸 𝑚 𝑐 sin(?? + 𝜔?) e. ? ⃑ = ?̂ 𝐸 𝑚 𝑐 cos(?? + 𝜔?) 22. In an experiment to measure the wavelength of light using a double slit, it is found that the fringes are too close together to easily count them. To spread out the fringe pattern, one could: a. Decrease the slit separation, ? b. Increase the slit separation, ? c. Decrease the width of each slit, ? d. Increase the width of each slit, ? e. Decrease the screen-to-slit distance, 𝐿

Physics 2C ELC Finals Study Jam – 7 – 27. Young’s Double Slit Experiment is performed with 589 ?? light and a distance of 3.00 ? between the slits and the screen. The third interference minimum is observed 7.50 ?? from the central maximum. Determine the spacing of the slits. Express your answer in millimeters up to 3 decimal places. 28. Consider a single slit diffraction pattern for a slit of width ? . It is observed that for light of wavelength 400 ?? , the angle between the first minimum and central maximum is 4 × 10 −3 ?𝑎?𝑖𝑎?? . The value of ? is: a. 1 × 10 −5 ? b. 1 × 10 −4 ? c. 1 × 10 −3 ? d. 2 × 10 −4 ? e. 5 × 10 −5 ? 29. Magnesium fluoride which has an index of refraction of 1.38 is used as antireflective coating on a piece of glass ( ? = 1.50 ). What should that minimum thickness ? of this film be to minimize reflection of 450 ?? light? Express your answer in nanometers to one decimal place. 30. In a practical double slit interference experiment, ? is the distance between the centers of the slits and 𝑎 is the width of each slit. The intensity distribution of the pattern formed on the screen is shown below. An interference maximum is missing on either side of this pattern as indicated. Using this information, what is the relationship between ? and 𝑎 ? a. ? = 2𝑎 b. ? = 3𝑎 c. 3? = 2𝑎 d. ? = √3 𝑎 e. ? = √2 𝑎 Incident light ray Air ( ? = 1.00 ) Magnesium fluoride ( ? = 1.38) Glass ( ? = 1.50 ) Missing bright fringe

Physics 2C ELC Finals Study Jam – 8 – 31. A ray of light passes through three media as shown. Rank the speeds of light in these media. a. ? 1 > ? 3 > ? 2 b. ? 1 > ? 2 > ? 3 c. ? 3 > ? 2 > ? 1 d. ? 2 > ? 3 > ? 1 e. ? 3 > ? 1 > ? 2 32. Light traveling in water ( ? ?𝑎𝑡𝑒𝑟 = 1.33 ) strikes a plastic block at an angle of incidence of 51.4° . Part of the beam is reflected and part is refracted. If the index of refraction of the plastic is 2.13, what is the angle ? between the reflected and refracted beams? a. 29.2° b. 38.6° c. 60.8° d. 90.0° e. 99.4° 33. The rectangular metal tank shown is filled with an unknown liquid. The observer, whose eye is level with the top of the tank, can just see corner E. What is the index of refraction of this liquid, up to 2 decimal places? 34. The image of an upright candle, formed using a convex mirror, is always: a. Virtual, upright, and smaller than the candle b. Virtual, inverted, and smaller than the candle c. Real, upright, and smaller than the candle d. Virtual, upright, and larger than the candle e. Virtual, inverted, and larger than the candle 35. An object is 10 ?? in front of a converging lens of focal length 30 ?? . The image is: a. Virtual and larger than the object b. Virtual and the same size as the object c. Virtual and smaller than the object d. Real and larger than the object e. Real and smaller than the object

Physics 2C ELC Finals Study Jam – 10 – 41. Consider the slow adiabatic expansion of an ideal gas from an initial state A to a final state B. Which of the following statements is not true? a. The mechanical work done by the gas is ∫ 𝑃?? 𝑉 ? 𝑉 ? . b. 𝑃 ? ? ? 𝛾 = 𝑃 ? ? ? 𝛾 . c. No heat flows into or out of the gas. d. The change of internal energy of the gas is − ∫ 𝑃?? 𝑉 ? 𝑉 ? . e. The temperature of the gas remains constant. 42. An object is located 40 ?? from the first of two thin converging lenses of focal lengths 20 ?? and 10 ?? , respectively, as shown in the figure above. The lenses are separated by 30 ?? . The final image formed by the two-lens system is located: a. 5.0 ?? to the right of the second lens b. 13.3 ?? to the left of the second lens c. 13.3 ?? to the right of the second lens d. 100 ?? to the left of the second lens e. Indefinitely far to the right of the second lens 43. A helium-filled balloon is used to suspend a mass of 300 ?𝑔 in air. If the mass of the balloon is neglected, which of the following gives the approximate volume of helium required? (The density of air is 1.29 ?𝑔/? 3 and the density of helium is 0.18 ?𝑔/? 3 .) a. 50 ? 3 b. 95 ? 3 c. 135 ? 3 d. 270 ? 3 e. 540 ? 3 44. Light from a laser falls on a pair of very narrow slits separated by 0.5 ?? , and bright fringes separated by 1.0 ?? are observed on a distant screen. If the frequency of the laser light is doubled, what will be the separation of the bright fringes? a. 0.25 ?? b. 0.5 ?? c. 1.0 ?? d. 2.0 ?? e. 2.5 ??

Physics 2C ELC Finals Study Jam – 11 – 45. The mean-squared speed ( ? 2 ) of molecules of mass ? of an ideal gas at temperature 𝑇 is: a. 0 b. 𝑘𝑇 𝑚 c. 2𝑘𝑇 𝑚 d. 3𝑘𝑇 𝑚 e. 8𝑘𝑇 𝑚 46. A sound wave with velocity of 340 ?/? diffracts out of a speaker enclosure with an opening that is a long rectangular slit 0.14 ? across. At about what frequency will the sound first vanish at an angle of 45° from the normal to the speaker face? a. 850 ?? b. 1700 ?? c. 3400 ?? d. 4200 ?? e. 5100 ?? 47. The side view of an optical fiber is shown in the figure below. The optical fiber has an index of refraction, ? , and is surrounded by free space. What angles of incidence, ? , will result in the light staying in the optical fiber? a. sin −1 (√? 2 − 1 ) < ? < sin −1 (√? 2 + 1 ) b. ? < sin −1 (√? 2 + 1 ) c. ? < sin −1 (√? 2 − 1 ) d. ? > sin −1 (√? 2 + 1 ) e. ? > sin −1 (√? 2 − 1 ) 48. Consider two horizontal plates with a thin film of air between them. For what values of the thickness of the film of air will the film, as seen by reflected light, appear bright if it is illuminated normally from above by blue light of wavelength 488 ?? ? a. 0, 122 ??, 244 ?? b. 0, 244 ??, 488 ?? c. 122 ??, 244 ??, 488 ?? d. 122 ??, 366 ??, 488 ?? e. 122 ??, 366 ??, 610 ??

Physics 2C ELC Finals Study Jam – 13 – 53. A Physics 2C student is measuring maxima and minima on a screen due to coherent laser light ( ? = 700 ?? ) incident upon a double slit. The slits in the slide are separated by a distance ? . The screen is 2.0 ? away from the two slits. The student is supposed to measure the distance ? along the screen from a given maximum to the central maximum. The student mistakenly measures the distance along the screen from the ? = +3 maximum on one side of the central maximum to the ? = 3 minimum on the other side of the central maximum, as shown in the picture below. In the picture below, dark spots correspond to the minima and white spots correspond to the maxima. What is the value of ? if the student measures 0.008 ? ? a. 0.175 ?? b. 0.44 ?? c. 0.52 ?? d. 0.96 ?? e. 1.1 ?? 54. If the speed of sound is 340 ?/? , the length of the shortest open-closed pipe that resonates at 218 ?? is: a. 17 ?? b. 23 ?? c. 39 ?? d. 51 ?? e. 78 ?? 55. A bat moving at 5 ?/? is flying toward an insect. If the bat emits a 40.0 ??? chirp and receives back an echo at 40.4 ??? , at what speed is the insect moving (with respect to the ground)? Take the speed of sound in air to be 343 ?/? . Use at least 3 decimal places in your calculations. a. 0 b. 1.62 ?/? away from the bat c. 1.62 ?/? toward the bat d. 3.29 ?/? away from the bat e. 3.29 ?/? toward from the bat 𝐿 ?

Physics 2C ELC Finals Study Jam – 14 – 56. A constant amount of an ideal gas undergoes a cyclic process ABCDA in the PV diagram shown below. The paths AB and CD are isothermal. What is the work done by the gas during one complete cycle, beginning and ending at A? Express your answer in ?? up to one decimal place. 57. A mass-spring system is initially at rest with the mass resting at the equilibrium position ? = 0 . At time ? = 0 , the mass is knocked to the left with a velocity ? 0 . If 𝜔 is the angular frequency of this oscillator, the position ?(?) of the mass is: a. ? 0 𝜔 sin (𝜔?) b. − ? 0 𝜔 sin (𝜔?) c. ? 0 𝜔 cos (𝜔?) d. − ? 0 𝜔 cos (𝜔?) e. −? 0 sin (𝜔? − 𝜋 3 ) 58. An ice cube made of pure water is floating in a glass of salt water that is filled entirely to the brim. Salt water is denser than pure water. When the ice cube melts, the water level will: a. Stay the same, right at the brim. b. Rise, causing the water to spill. c. Fall. 59. At a particular instant of time, the electric field in a plane EM wave points along the +? ̂ direction and the magnetic field points along +? ̂ . Which of the following could describe the electric field of this wave? a. ? ⃑ = ? ̂? 𝑚 sin(?? + 𝜔?) b. ? ⃑ = ? ̂? 𝑚 sin(?? − 𝜔?) c. ? ⃑ = ? ̂? 𝑚 sin(?? + 𝜔?) d. ? ⃑ = ? ̂? 𝑚 sin(?? − 𝜔?) e. ? ⃑ = ? ̂? 𝑚 sin(?? + 𝜔?)

Physics 2C ELC Finals Study Jam – 16 – Answer Key 1. C 2. C 3. A 4. A 5. D 6. 1.91 7. B 8. 1.37 9. C 10. A 11. A 12. 6 13. E 14. C 15. B 16. B 17. C 18. B 19. 41.18 20. E 21. A 22. A 23. E 24. B 25. B 26. D 27. 0.589 28. B 29. 81.5 30. B 31. E 32. E 33. 1.25 34. A 35. A 36. 5.92 37. E 38. A 39. E 40. D 41. E 42. A 43. D 44. B 45. D 46. C 47. C 48. E 49. A 50. E 51. 0.625 52. A 53. D 54. C 55. D 56. 306.5 57. B 58. B 59. C 60. C 61. D 62. D 63. C