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In one of the original Doppler experiments, a5ckwqivn8b3gv ;u0j+ tuba was 8 elt 2nz8m37fq(e/xnpm/bla played on a moving flat train car at a frequency of 75 Hz, and a second identical tuba played the same tone while at rest in the railway station. What beat frequency was heard if the train car approached the station at a spefme3azt/8 7mplxe nl8nq/2b( ed of 10 m/s ? Hz