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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 |
---|---|---|---|

14 | Assuming that the wave speed varies little when sound waves are traveling though a material that suddenly changes density by 10%, what percentage of the incident wave intensity is reflected? 1) < 1 % 2) 5 % 3) 10 % 4) 20 % 5) 30% | < 1 % | |

8 | Masses are distributed in the xy-plane as follows: 10 kg at (2.0, 6.0) m, 4.0 kg at (2.0, 0.0) m, and 6.0 kg at (0.0, 3.0) m. Where would a 20-kg mass need to be positioned so that the center of gravity of the resulting four mass system would be at the origin? | (-1.4, -3.9) m | |

8 | A hoop of radius 1.0 m is placed in the first quadrant of an xy-coordinate system with its rim touching both the x-axis and the y-axis. What are the coordinates of its center of gravity? | (1.0, 1.0) m | |

8 | An object of mass m and moment of inertia I has rotational kinetic energy KR. Its angular momentum is: | (2 IKR)^1/2 | |

10 | Different units can be used for length: m and cm, and of these two, m is the larger by a factor of 100. Different units can also be used for R: (1) J/mol*K, (2) L*atm/mol*K, and (3) (N/m^2)*m3/mol*K. Which of these units for R is the largest? Hint: When expressing R in each of these units, which expression has the lowest numerical factor? (1L = 10-3 m3, 1 atm = 1.01*10^5 Pa) | (2) L*atm/mol*K | |

10 | The internal energy of a monatomic ideal gas is equal to which of the following? | (3/2)PV | |

1 | Which point is nearest the x axis? 1) (-3, 4) 2) (4, 5) 3) (-5, 3) 4) (5, -2) 5) (-4, 4) | (5, -2) | |

12 | What is the work done on the gas as it expands from pressure P1 and volume V1 to pressure P2 and volume V2 along the indicated straight line? | (P1 + P2)(V1 - V2)/2 | |

6 | A 20-kg object sitting at rest is struck elastically in a head-on collision with a 10-kg object initially moving at +3.0 m/s. Find the final velocity of the 20-kg object after the collision. | +2.0 m/s | |

4 | A 10.0-kg mass is placed on a 25.0o incline and friction keeps it from sliding. The coefficient of static friction in this case is 0.580 and the coefficient of sliding friction is 0.520. The mass is given a shove causing it to slide down the incline. Taking down the incline as positive, what is the acceleration of the mass while it is sliding? | -0.477m/s^2 | |

8 | A 3.0-m rod is pivoted about its left end. A force of 6.0 N is applied perpendicular to the rod at a distance of 1.2 m from the pivot causing a ccw torque, and a force of 5.2 N is applied at the end of the rod 3.0 m from the pivot. The 5.2 N is at an angle of 30o to the rod and causes a cw torque. What is the net torque about the pivot? | -0.6 Nm | |

6 | Two billiard balls have velocities of 2.0 m/s and -1.0 m/s when they meet in an elastic head-on collision. What is the final velocity of the first ball after collision? | -1.0 m/s | |

11 | A puddle holds 150 g of water. If 0.50 g of water evaporates from the surface, what is the approximate temperature change of the remaining water? (Lv = 540 cal/g) | -1.8 C° | |

5 | A hill is 100 m long and makes an angle of 12° with the horizontal. As a 50-kg jogger runs up the hill, how much work does gravity do on the jogger? | -10000 J | |

10 | Carbon dioxide forms into a solid (dry ice) at approximately -157°F. What temperature in degrees Celsius does this correspond to? | -105°C |