quiz11

  1. At a distance of 20.0m from a loudspeaker 1.00E-6J of energy cross your eardrum (Area=0.500cm^2...careful on units!!!!!) in a time of 1.00s. What is the intensity at 100.0m from the loudspeaker?
    a) 2.00E-2 Watts/m^2
    b) 8.00E-2 Watts/m^2
    c) 0.500 Watts/m^2
    d) 2.00E-4 Watts/m^2
    e) 8.00E-4 Watts/m^2
    No answer given yet
  2. A train heads toward you at 30.0m/s and blows its whistle (440Hz when still) as you drive toward the train at 25m/s. What frequency do you observe?  v(air)=340m/s
    a) 447.1Hz
    b) 434.1Hz
    c) 516.8Hz
    d) 440Hz
    e) 518.1Hz
    No answer given yet
  3. A standing wave on a string tied at both ends has five nodes (including the ends....draw this). The frequency for this wave is 400Hz. The wave speed is 100m/s on the string. What is the length of the string and fundamental (n=1) frequency.
    a) 0.20m, 100Hz
    b) 0.125m, 2000Hz
    c) 0.125m, 80Hz
    d) 0.50m, 400Hz
    e) 0.50m, 100Hz
    No answer given yet