Not sure how to do this temp and freq problem

Can someone help me work these out!?

1) A sound travels 1,047 meters in 3 seconds in air. Find the air temperature. (Answer 31.3 degrees C??)

2) A guitar string plays a fundamental frequency of 400 Hz. Find the
frequency played if the string were twice as long and twice as tight. (Answer is 283 Hz)

OlderDan
Homework Helper
xxiangel said:
Can someone help me work these out!?

1) A sound travels 1,047 meters in 3 seconds in air. Find the air temperature. (Answer 31.3 degrees C??)

2) A guitar string plays a fundamental frequency of 400 Hz. Find the
frequency played if the string were twice as long and twice as tight. (Answer is 283 Hz)

Do a bit of research in your textbook, or go to google and search on "speed of sound" and "vibrating string". Then give these a try on your own. If you still need some help, show us what you did.

FredGarvin
Here are some hints:

1) In a perfect gas there is a relationship between the speed of sound, c, and the ratio of specific heats, $$\gamma$$, gravity, $$g$$, ideal gas constant, $$R$$, and temperature, $$T$$. You have information to calculate c in your question.

2) There is an equation for calculating the fundamental frequency of a string. In that equation is the term for the length. What can you glean by doubling the length in that equation?

Let's see what you have done so far.

Chi Meson