# A few physics questions?

1. What is the speed of sound in air that has a temperature of 25 degrees C?

2. A sound wave traveling through 17 degree C air has a wavelength of 2 meters. What is the frequency of the sound wave?

3. During a thunderstorm, the temperature is 10 degrees C. If you see a lightning strike and then hear the thunder 2 seconds later, how far away did the lightning strike?

Relevance

(1) v=331.3+0.606t = 331.3+15.15= 346.45[m/s]

(2) v=331.3+10.302= 341.602m/s

f=v/λ = 341.602/2= 170.801= 170.8[Hz]

(3) v=331.3+6.06= 337.36m/s

d=vt = 337.36*2= 674.72[m]

331.3+0.606t(usa) , 331.5+0.6t(jpn,ger,fra,ita)

http://en.wikipedia.org/wiki/Speed_of_sound

http://ja.wikipedia.org/wiki/%E9%9F%B3%E9%80%9F

• at 0 degrees C i.e. 273 kelvin the speed of sound in air is 332 m/s

i.e T1 = 273K and v1 = 332 m/s

now at 25 degrees i.e 298 kelvin

T2 = 298K and v2 = ?

since speed of sound and kelvin temperature( T ) are related as

v1/v2 = T1/T2

v2= T2/T1*v1

i.e v2 = 298/273*332

v2=362(approx)

ie the speed of sound in air at 25 degrees is nearly 362 m/s

similarly find the speed of sound in air at 17 degrees i.e 290K, which will be nearly 352 m/s

then by the relation v=l*f where v is velocity, l is wavelength and f is frequency,

f = v/l

f = 352/2 i.e 176 per sec ie 172 hertz

for 3rd question find the speed of sound in air at 10 degrees i.e 283K, which will be 344 m/s

then since light travels faster than sound ie nearly 3*10^8 m/s (and since it is the same at every temperature for air.) this speed is very high as compared to 344 m/s so we just neglect the time the light took to reach our eyes which would be very small so

just use the formula v= d/t where d is distance for the sound ..

i.e 344=d/2

so distance is 688 m.