What frequency will you hear if a truck is driving toward you at 20 m/s sounding a horn of frequency 300 hz. assume the speed of sound to be 340 m/s.

=319Hz

Explanation:

This question is on sound waves

General formulae;

Frequency of observer= f of source*[ (v of sound+ v of observer)/(v of sound-v of source)]

where f is frequency and v is velocity

Given;

Velocity of sound = 340m/s

frequency of source = 300 Hz

Velocity of observer=0m/s

Velocity of source/truck= 20m/s

Substitute values in the formulae;

Frequency of observer= 300× {(340+0)/(340-20)}

                                       =300×{ 340/320}

                                       =300×340/320

                                       =318.75

                                       =319Hz

the bal will not change its velocity.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.