Asiren mounted on the roof of firehouse emits sound at a frequency of 815 hz. a steady wind is blowing with a speed of 14.4 m/s. take the speed of sound in calm air to be 343 m/s (a) find the wavelength of the sound upwind of the siren. (b) find the wavelength of the sound downwind of the siren m f he or she is approaching from an upwind (c) firefighters are approaching the siren from various directions at 19.5 m/s. what frequency does a firefighter hear position, so that he or she is moving in the direction in which the wind is blowing? hz (d) what frequency does a firefighter hear if he or she is approaching from a downwind position and moving against the wind?

Explanation:

Wind increases the velocity of sound in case of downwind and decreases in case of upwind .

a ) In this case velocity of sound =343 - 14.4 = 328.6

wavelength = velocity / frequency = 328.6/ 815 = 40.32 cm

b ) In this case velocity of sound = 343+14.4 = 357.4

Wavelength = 357.4 / 815 = 43.85 cm

c) In this case apparent frequency = 815 x ( 328.6 + 19.5 )/ 328.6

= 863.36 (sound is moving against the wind )

d ) Apparent frequency =815 x ( 357 + 19.5 ) / 357 ( sound is moving in the direction of wind )

= 859.51

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explanation:

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.