Halliday 2 Cap 18 - P18 076

Transcript

76. Let the frequencies of sound heard by the person from the left and right forks be fl and fr , respectively. (a) If the speeds of both forks are u, then fl,r = f v/(v ± u) and
 1 1 2f uv fbeat = |fr − fl | = f v − = 2 v−u v+u v − u2 2(440 Hz)(30.0 m/s)(343 m/s) = (343 m/s)2 − (30.0 m/s)2 = 77.6 Hz . (b) If the speed of the listener is u, then fl,r = f (v ± u)/v and
 u 30.0 m/s fbeat = |fl − fr | = 2f = 2(440 Hz) = 77.0 Hz . v 343 m/s