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The following physics responses are provided by a student and, as such, should be considered in that context. While every effort is made for accuracy, absolute correctness cannot be fully guaranteed.

C | I | Question | Answer |
---|---|---|---|

13 | Consider two identical and symmetrical wave pulses on a string. Suppose the first pulse reaches the fixed end of the string and is reflected back and then meets the second pulse. When the two pulses overlap exactly, the superposition principle predicts that the amplitude of the resultant pulses, at that moment, will be what factor times the amplitude of one of the original pulses? | 0 | |

11 | The emissivity of an ideal reflector has which of the following values? | 0 | |

6 | A billiard ball is moving in the x-direction at 30.0 cm/s and strikes another billiard ball moving in the y-direction at 40.0 cm/s. As a result of the collision, the first ball moves at 50.0 cm/s, and the second ball stops. What is the change in kinetic energy of the system as a result of the collision? | 0 | |

2 | An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction, what is the sign associated with the average velocity of the object? | 0 (no sign) | |

1 | The information on a one-gallon paint can is that the coverage, when properly applied, is 450 ft2. One gallon is 231 in3. What is the average thickness of the paint in such an application? | 0.0036 in | |

13 | A 0.20-kg object is oscillating on a spring with a spring constant of k = 15 N/m. What is the potential energy of the system when the object displacement is 0.040 m, exactly half the maximum amplitude? | 0.012 J | |

9 | The bottom of a flat-bottomed aluminum boat has an area of 4.0 m2 and the boat's mass is 60 kg. When set afloat in water, how far below the water surface is the boat bottom? (water density = 1.0*10^3 kg/m3) | 0.015 m | |

10 | A helium-filled weather balloon has a 0.90 m radius at liftoff where air pressure is 1.0 atm and the temperature is 298 K. When airborne, the temperature is 210 K, and its radius expands to 3.0 m. What is the pressure at the airborne location? | 0.019 atm | |

13 | A mass on a spring vibrates in simple harmonic motion at a frequency of 4.0 Hz and an amplitude of 8.0 cm. If a timer is started when its displacement is a maximum (hence x = 8 cm when t = 0), what is the displacement of the mass when t = 3.7 s? | 0.025 m | |

4 | A hockey puck moving at 7.0 m/s coasts to a halt in 75 m on a smooth ice surface. What is the coefficient of friction between the ice and the puck? | 0.033 | |

9 | Water (density = 1*10^3 kg/m3) flows at 10 m/s through a pipe with radius 0.030 m. The pipe goes up to the second floor of the building, 2.0 m higher, and the pressure remains unchanged. What is the radius of the pipe on the second floor? | 0.034 m | |

8 | Two hoops or rings (I = MR^2) are centered, lying on a turntable. The smaller ring has radius = 0.050 m; the larger has radius = 0.10 m. Both have a mass of 3.0 kg. What is the total moment of inertia as the turntable spins? Ignore the mass of the turntable. | 0.038 kg*m^2 | |

6 | Two skaters, both of mass 75 kg, are on skates on a frictionless ice pond. One skater throws a 0.3-kg ball at 5 m/s to his friend, who catches it and throws it back at 5 m/s. When the first skater has caught the returned ball, what is the velocity of each of the two skaters? | 0.04 m/s, moving apart | |

7 | A point on the rim of a 0.25-m-radius fan blade has centripetal acceleration of 0.20 m/s2. Find the centripetal acceleration of a point 0.05 m from the center of the same wheel. | 0.04 m/s^2 | |

11 | A silver bar of length 30 cm and cross-sectional area 1.0 cm2 is used to transfer heat from a 100°C reservoir to a 0°C block of ice. How much ice is melted per second? (For silver, k = 427 J/s×m×°C. For ice, Lf = 334 000 J/kg.) | 0.043 g/s |

Time lapse: 0.02243 s.

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