An owl fiying at 30 m/s emits a cry whose frequency is 540 Hz. A mockingbird is moving in the same direction as the owl at 14 m/s. (Assume the speed of sound is 343 m/s. (a) What frequency does the mockingbird hear (in Hz) as the owl approaches the mockingbird? (b) What frequency does the mockingbird hear (in Hz) after the owl passes the mockingbind?